chiark / gitweb /
Tents: mark squares as non-tents with {Shift,Control}-cursor keys.
[sgt-puzzles.git] / guess.c
diff --git a/guess.c b/guess.c
index d31d0613f723b70f192896fc6214cf1599b30b69..df9b7f628c9d117d614257d93b3f44794b20fed5 100644 (file)
--- a/guess.c
+++ b/guess.c
@@ -39,10 +39,11 @@ typedef struct pegrow {
 struct game_state {
     game_params params;
     pegrow *guesses;  /* length params->nguesses */
+    int *holds;
     pegrow solution;
     int next_go; /* from 0 to nguesses-1;
                     if next_go == nguesses then they've lost. */
-    int solved;
+    int solved;   /* +1 = win, -1 = lose, 0 = still playing */
 };
 
 static game_params *default_params(void)
@@ -65,7 +66,7 @@ static void free_params(game_params *params)
     sfree(params);
 }
 
-static game_params *dup_params(game_params *params)
+static game_params *dup_params(const game_params *params)
 {
     game_params *ret = snew(game_params);
     *ret = *params;                   /* structure copy */
@@ -144,7 +145,7 @@ static void decode_params(game_params *params, char const *string)
     }
 }
 
-static char *encode_params(game_params *params, int full)
+static char *encode_params(const game_params *params, int full)
 {
     char data[256];
 
@@ -155,7 +156,7 @@ static char *encode_params(game_params *params, int full)
     return dupstr(data);
 }
 
-static config_item *game_configure(game_params *params)
+static config_item *game_configure(const game_params *params)
 {
     config_item *ret;
     char buf[80];
@@ -198,7 +199,7 @@ static config_item *game_configure(game_params *params)
     return ret;
 }
 
-static game_params *custom_params(config_item *cfg)
+static game_params *custom_params(const config_item *cfg)
 {
     game_params *ret = snew(game_params);
 
@@ -212,7 +213,7 @@ static game_params *custom_params(config_item *cfg)
     return ret;
 }
 
-static char *validate_params(game_params *params, int full)
+static char *validate_params(const game_params *params, int full)
 {
     if (params->ncolours < 2 || params->npegs < 2)
        return "Trivial solutions are uninteresting";
@@ -263,7 +264,7 @@ static void free_pegrow(pegrow pegs)
     sfree(pegs);
 }
 
-static char *new_game_desc(game_params *params, random_state *rs,
+static char *new_game_desc(const game_params *params, random_state *rs,
                           char **aux, int interactive)
 {
     unsigned char *bmp = snewn(params->npegs, unsigned char);
@@ -286,7 +287,7 @@ newcol:
     return ret;
 }
 
-static char *validate_desc(game_params *params, char *desc)
+static char *validate_desc(const game_params *params, const char *desc)
 {
     unsigned char *bmp;
     int i;
@@ -309,7 +310,8 @@ static char *validate_desc(game_params *params, char *desc)
     return NULL;
 }
 
-static game_state *new_game(midend *me, game_params *params, char *desc)
+static game_state *new_game(midend *me, const game_params *params,
+                            const char *desc)
 {
     game_state *state = snew(game_state);
     unsigned char *bmp;
@@ -319,6 +321,7 @@ static game_state *new_game(midend *me, game_params *params, char *desc)
     state->guesses = snewn(params->nguesses, pegrow);
     for (i = 0; i < params->nguesses; i++)
        state->guesses[i] = new_pegrow(params->npegs);
+    state->holds = snewn(params->npegs, int);
     state->solution = new_pegrow(params->npegs);
 
     bmp = hex2bin(desc, params->npegs);
@@ -327,12 +330,13 @@ static game_state *new_game(midend *me, game_params *params, char *desc)
        state->solution->pegs[i] = (int)bmp[i];
     sfree(bmp);
 
+    memset(state->holds, 0, sizeof(int) * params->npegs);
     state->next_go = state->solved = 0;
 
     return state;
 }
 
-static game_state *dup_game(game_state *state)
+static game_state *dup_game(const game_state *state)
 {
     game_state *ret = snew(game_state);
     int i;
@@ -342,6 +346,8 @@ static game_state *dup_game(game_state *state)
     ret->guesses = snewn(state->params.nguesses, pegrow);
     for (i = 0; i < state->params.nguesses; i++)
        ret->guesses[i] = dup_pegrow(state->guesses[i]);
+    ret->holds = snewn(state->params.npegs, int);
+    memcpy(ret->holds, state->holds, sizeof(int) * state->params.npegs);
     ret->solution = dup_pegrow(state->solution);
 
     return ret;
@@ -354,23 +360,29 @@ static void free_game(game_state *state)
     free_pegrow(state->solution);
     for (i = 0; i < state->params.nguesses; i++)
        free_pegrow(state->guesses[i]);
+    sfree(state->holds);
     sfree(state->guesses);
 
     sfree(state);
 }
 
-static char *solve_game(game_state *state, game_state *currstate,
-                       char *aux, char **error)
+static char *solve_game(const game_state *state, const game_state *currstate,
+                        const char *aux, char **error)
 {
     return dupstr("S");
 }
 
-static char *game_text_format(game_state *state)
+static int game_can_format_as_text_now(const game_params *params)
+{
+    return TRUE;
+}
+
+static char *game_text_format(const game_state *state)
 {
     return NULL;
 }
 
-static int is_markable(game_params *params, pegrow pegs)
+static int is_markable(const game_params *params, pegrow pegs)
 {
     int i, nset = 0, nrequired, ret = 0;
     pegrow colcount = new_pegrow(params->ncolours);
@@ -407,9 +419,12 @@ struct game_ui {
 
     int drag_col, drag_x, drag_y; /* x and y are *center* of peg! */
     int drag_opeg; /* peg index, if dragged from a peg (from current guess), otherwise -1 */
+
+    int show_labels;                   /* label the colours with letters */
+    pegrow hint;
 };
 
-static game_ui *new_ui(game_state *state)
+static game_ui *new_ui(const game_state *state)
 {
     game_ui *ui = snew(game_ui);
     memset(ui, 0, sizeof(game_ui));
@@ -423,52 +438,81 @@ static game_ui *new_ui(game_state *state)
 
 static void free_ui(game_ui *ui)
 {
+    if (ui->hint)
+        free_pegrow(ui->hint);
     free_pegrow(ui->curr_pegs);
     sfree(ui->holds);
     sfree(ui);
 }
 
-static char *encode_ui(game_ui *ui)
+static char *encode_ui(const game_ui *ui)
 {
     char *ret, *p, *sep;
     int i;
 
     /*
      * For this game it's worth storing the contents of the current
-     * guess.
+     * guess, and the current set of holds.
      */
     ret = snewn(40 * ui->curr_pegs->npegs, char);
     p = ret;
     sep = "";
     for (i = 0; i < ui->curr_pegs->npegs; i++) {
-        p += sprintf(p, "%s%d", sep, ui->curr_pegs->pegs[i]);
+        p += sprintf(p, "%s%d%s", sep, ui->curr_pegs->pegs[i],
+                     ui->holds[i] ? "_" : "");
         sep = ",";
     }
+    *p++ = '\0';
     assert(p - ret < 40 * ui->curr_pegs->npegs);
-    return sresize(ret, p - ret + 1, char);
+    return sresize(ret, p - ret, char);
 }
 
-static void decode_ui(game_ui *ui, char *encoding)
+static void decode_ui(game_ui *ui, const char *encoding)
 {
     int i;
-    char *p = encoding;
+    const char *p = encoding;
     for (i = 0; i < ui->curr_pegs->npegs; i++) {
         ui->curr_pegs->pegs[i] = atoi(p);
         while (*p && isdigit((unsigned char)*p)) p++;
+        if (*p == '_') {
+            /* NB: old versions didn't store holds */
+            ui->holds[i] = 1;
+            p++;
+        } else
+            ui->holds[i] = 0;
         if (*p == ',') p++;
     }
     ui->markable = is_markable(&ui->params, ui->curr_pegs);
 }
 
-static void game_changed_state(game_ui *ui, game_state *oldstate,
-                               game_state *newstate)
+static void game_changed_state(game_ui *ui, const game_state *oldstate,
+                               const game_state *newstate)
 {
     int i;
 
-    /* just clear the row-in-progress when we have an undo/redo. */
-    for (i = 0; i < ui->curr_pegs->npegs; i++)
-       ui->curr_pegs->pegs[i] = 0;
-    ui->markable = FALSE;
+    if (newstate->next_go < oldstate->next_go) {
+        sfree(ui->hint);
+        ui->hint = NULL;
+    }
+
+    /* Implement holds, clear other pegs.
+     * This does something that is arguably the Right Thing even
+     * for undo. */
+    for (i = 0; i < newstate->solution->npegs; i++) {
+        if (newstate->solved)
+            ui->holds[i] = 0;
+        else
+            ui->holds[i] = newstate->holds[i];
+       if (newstate->solved || (newstate->next_go == 0) || !ui->holds[i]) {
+           ui->curr_pegs->pegs[i] = 0;
+       } else
+            ui->curr_pegs->pegs[i] =
+                newstate->guesses[newstate->next_go-1]->pegs[i];
+    }
+    ui->markable = is_markable(&newstate->params, ui->curr_pegs);
+    /* Clean up cursor position */
+    if (!ui->markable && ui->peg_cur == newstate->solution->npegs)
+       ui->peg_cur--;
 }
 
 #define PEGSZ   (ds->pegsz)
@@ -529,13 +573,13 @@ struct game_drawstate {
     int drag_col, blit_ox, blit_oy;
 };
 
-static void set_peg(game_params *params, game_ui *ui, int peg, int col)
+static void set_peg(const game_params *params, game_ui *ui, int peg, int col)
 {
     ui->curr_pegs->pegs[peg] = col;
     ui->markable = is_markable(params, ui->curr_pegs);
 }
 
-static int mark_pegs(pegrow guess, pegrow solution, int ncols)
+static int mark_pegs(pegrow guess, const pegrow solution, int ncols)
 {
     int nc_place = 0, nc_colour = 0, i, j;
 
@@ -575,11 +619,10 @@ static int mark_pegs(pegrow guess, pegrow solution, int ncols)
     return nc_place;
 }
 
-static char *encode_move(game_state *from, game_ui *ui)
+static char *encode_move(const game_state *from, game_ui *ui)
 {
     char *buf, *p, *sep;
-    int len, i, solved;
-    pegrow tmppegs;
+    int len, i;
 
     len = ui->curr_pegs->npegs * 20 + 2;
     buf = snewn(len, char);
@@ -587,33 +630,139 @@ static char *encode_move(game_state *from, game_ui *ui)
     *p++ = 'G';
     sep = "";
     for (i = 0; i < ui->curr_pegs->npegs; i++) {
-       p += sprintf(p, "%s%d", sep, ui->curr_pegs->pegs[i]);
+       p += sprintf(p, "%s%d%s", sep, ui->curr_pegs->pegs[i],
+                     ui->holds[i] ? "_" : "");
        sep = ",";
     }
     *p++ = '\0';
     assert(p - buf <= len);
     buf = sresize(buf, len, char);
 
-    tmppegs = dup_pegrow(ui->curr_pegs);
-    solved = mark_pegs(tmppegs, from->solution, from->params.ncolours);
-    solved = (solved == from->params.ncolours);
-    free_pegrow(tmppegs);
+    return buf;
+}
 
-    for (i = 0; i < from->solution->npegs; i++) {
-       if (!ui->holds[i] || solved) {
-           ui->curr_pegs->pegs[i] = 0;
-       }
-       if (solved) ui->holds[i] = 0;
+static void compute_hint(const game_state *state, game_ui *ui)
+{
+    /* Suggest the lexicographically first row consistent with all
+     * previous feedback.  This is not only a useful hint, but also
+     * a reasonable strategy if applied consistently.  If the user
+     * uses hints in every turn, they may be able to intuit this
+     * strategy, or one similar to it.  I (Jonas Kölker) came up
+     * with something close to it without seeing it in action. */
+
+    /* Some performance characteristics: I want to ask for each n,
+     * how many solutions are guessed in exactly n guesses if you
+     * use the hint in each turn.
+     *
+     * With 4 pegs and 6 colours you get the following histogram:
+     *
+     *  1 guesses:     1 solution
+     *  2 guesses:     4 solutions
+     *  3 guesses:    25 solutions
+     *  4 guesses:   108 solutions
+     *  5 guesses:   305 solutions
+     *  6 guesses:   602 solutions
+     *  7 guesses:   196 solutions
+     *  8 guesses:    49 solutions
+     *  9 guesses:     6 solutions
+     * (note: the tenth guess is never necessary.)
+     *
+     * With 5 pegs and 8 colours you get the following histogram:
+     *
+     *  1 guesses:     1 solution
+     *  2 guesses:     5 solutions
+     *  3 guesses:    43 solutions
+     *  4 guesses:   278 solutions
+     *  5 guesses:  1240 solutions
+     *  6 guesses:  3515 solutions
+     *  7 guesses:  7564 solutions
+     *  8 guesses: 14086 solutions
+     *  9 guesses:  4614 solutions
+     * 10 guesses:  1239 solutions
+     * 11 guesses:   175 solutions
+     * 12 guesses:     7 solutions
+     * 13 guesses:     1 solution
+     *
+     * The solution which takes too many guesses is {8, 8, 5, 6, 7}.
+     * The game ID is c8p5g12Bm:4991e5e41a. */
+
+    int mincolour = 1, maxcolour = 0, i, j;
+
+    /* For large values of npegs and ncolours, the lexicographically
+     * next guess make take a while to find.  Finding upper and
+     * lower limits on which colours we have to consider will speed
+     * this up, as will caching our progress from one invocation to
+     * the next.  The latter strategy works, since if we have ruled
+     * out a candidate we will never reverse this judgment in the
+     * light of new information.  Removing information, i.e. undo,
+     * will require us to backtrack somehow.  We backtrack by fully
+     * forgetting our progress (and recomputing it if required). */
+
+    for (i = 0; i < state->next_go; ++i)
+        for (j = 0; j < state->params.npegs; ++j)
+            if (state->guesses[i]->pegs[j] > maxcolour)
+                maxcolour = state->guesses[i]->pegs[j];
+    maxcolour = min(maxcolour + 1, state->params.ncolours);
+
+increase_mincolour:
+    for (i = 0; i < state->next_go; ++i) {
+        if (state->guesses[i]->feedback[0])
+            goto next_iteration;
+        for (j = 0; j < state->params.npegs; ++j)
+            if (state->guesses[i]->pegs[j] != mincolour)
+                goto next_iteration;
+        ++mincolour;
+        goto increase_mincolour;
+    next_iteration:
+        ;
     }
-    ui->markable = is_markable(&from->params, ui->curr_pegs);
-    if (!ui->markable && ui->peg_cur == from->solution->npegs)
-       ui->peg_cur--;
 
-    return buf;
+    if (!ui->hint) {
+        ui->hint = new_pegrow(state->params.npegs);
+        for (i = 0; i < state->params.npegs; ++i)
+            ui->hint->pegs[i] = 1;
+    }
+
+    while (ui->hint->pegs[0] <= state->params.ncolours) {
+        for (i = 0; i < state->next_go; ++i) {
+            mark_pegs(ui->hint, state->guesses[i], maxcolour);
+            for (j = 0; j < state->params.npegs; ++j)
+                if (ui->hint->feedback[j] != state->guesses[i]->feedback[j])
+                    goto increment_pegrow;
+        }
+        /* a valid guess was found; install it and return */
+        for (i = 0; i < state->params.npegs; ++i)
+            ui->curr_pegs->pegs[i] = ui->hint->pegs[i];
+
+        ui->markable = TRUE;
+        ui->peg_cur = state->params.npegs;
+        ui->display_cur = 1;
+        return;
+
+    increment_pegrow:
+        for (i = ui->hint->npegs;
+             ++ui->hint->pegs[--i], i && ui->hint->pegs[i] > maxcolour;
+             ui->hint->pegs[i] = mincolour);
+    }
+    /* No solution is compatible with the given hints.  Impossible! */
+    /* (hack new_game_desc to create invalid solutions to get here) */
+
+    /* For some values of npegs and ncolours, the hinting function takes a
+     * long time to complete.  To visually indicate completion with failure,
+     * should it ever happen, update the ui in some trivial way.  This gives
+     * the user a sense of broken(ish)ness and futility. */
+    if (!ui->display_cur) {
+        ui->display_cur = 1;
+    } else if (state->params.npegs == 1) {
+        ui->display_cur = 0;
+    } else {
+        ui->peg_cur = (ui->peg_cur + 1) % state->params.npegs;
+    }
 }
 
-static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
-                           int x, int y, int button)
+static char *interpret_move(const game_state *from, game_ui *ui,
+                            const game_drawstate *ds,
+                            int x, int y, int button)
 {
     int over_col = 0;           /* one-indexed */
     int over_guess = -1;        /* zero-indexed */
@@ -625,22 +774,34 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
     int guess_ox = GUESS_X(from->next_go, 0);
     int guess_oy = GUESS_Y(from->next_go, 0);
 
+    /*
+     * Enable or disable labels on colours.
+     */
+    if (button == 'l' || button == 'L') {
+        ui->show_labels = !ui->show_labels;
+        return "";
+    }
+
     if (from->solved) return NULL;
 
-    if (x >= COL_OX && x <= (COL_OX + COL_W) &&
-        y >= COL_OY && y <= (COL_OY + COL_H)) {
+    if (x >= COL_OX && x < (COL_OX + COL_W) &&
+        y >= COL_OY && y < (COL_OY + COL_H)) {
         over_col = ((y - COL_OY) / PEGOFF) + 1;
+        assert(over_col >= 1 && over_col <= ds->colours->npegs);
     } else if (x >= guess_ox &&
-               y >= guess_oy && y <= (guess_oy + GUESS_H)) {
-        if (x <= (guess_ox + GUESS_W)) {
+               y >= guess_oy && y < (guess_oy + GUESS_H)) {
+        if (x < (guess_ox + GUESS_W)) {
             over_guess = (x - guess_ox) / PEGOFF;
+            assert(over_guess >= 0 && over_guess < ds->solution->npegs);
         } else {
             over_hint = 1;
         }
-    } else if (x >= guess_ox && x <= (guess_ox + GUESS_W) &&
+    } else if (x >= guess_ox && x < (guess_ox + GUESS_W) &&
                y >= GUESS_OY && y < guess_oy) {
         over_past_guess_y = (y - GUESS_OY) / PEGOFF;
         over_past_guess_x = (x - guess_ox) / PEGOFF;
+        assert(over_past_guess_y >= 0 && over_past_guess_y < from->next_go);
+        assert(over_past_guess_x >= 0 && over_past_guess_x < ds->solution->npegs);
     }
     debug(("make_move: over_col %d, over_guess %d, over_hint %d,"
            " over_past_guess (%d,%d)", over_col, over_guess, over_hint,
@@ -720,6 +881,9 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
         if (button == CURSOR_UP && ui->colour_cur > 0)
             ui->colour_cur--;
         ret = "";
+    } else if (button == 'h' || button == 'H' || button == '?') {
+        compute_hint(from, ui);
+        ret = "";
     } else if (button == CURSOR_LEFT || button == CURSOR_RIGHT) {
         int maxcur = from->params.npegs;
         if (ui->markable) maxcur++;
@@ -730,8 +894,7 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
         if (button == CURSOR_LEFT && ui->peg_cur > 0)
             ui->peg_cur--;
         ret = "";
-    } else if (button == CURSOR_SELECT || button == ' ' || button == '\r' ||
-               button == '\n') {
+    } else if (IS_CURSOR_SELECT(button)) {
         ui->display_cur = 1;
         if (ui->peg_cur == from->params.npegs) {
             ret = encode_move(from, ui);
@@ -743,7 +906,9 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
         ui->display_cur = 1;
         set_peg(&from->params, ui, ui->peg_cur, 0);
         ret = "";
-    } else if (button == 'H' || button == 'h') {
+    } else if (button == CURSOR_SELECT2) {
+        if (ui->peg_cur == from->params.npegs)
+            return NULL;
         ui->display_cur = 1;
         ui->holds[ui->peg_cur] = 1 - ui->holds[ui->peg_cur];
         ret = "";
@@ -751,15 +916,15 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
     return ret;
 }
 
-static game_state *execute_move(game_state *from, char *move)
+static game_state *execute_move(const game_state *from, const char *move)
 {
     int i, nc_place;
     game_state *ret;
-    char *p;
+    const char *p;
 
     if (!strcmp(move, "S")) {
        ret = dup_game(from);
-       ret->solved = 1;
+       ret->solved = -1;
        return ret;
     } else if (move[0] == 'G') {
        p = move+1;
@@ -775,17 +940,22 @@ static game_state *execute_move(game_state *from, char *move)
            }
            ret->guesses[from->next_go]->pegs[i] = atoi(p);
            while (*p && isdigit((unsigned char)*p)) p++;
+            if (*p == '_') {
+                ret->holds[i] = 1;
+                p++;
+            } else
+                ret->holds[i] = 0;
            if (*p == ',') p++;
        }
 
        nc_place = mark_pegs(ret->guesses[from->next_go], ret->solution, ret->params.ncolours);
 
        if (nc_place == ret->solution->npegs) {
-           ret->solved = 1; /* win! */
+           ret->solved = +1; /* win! */
        } else {
            ret->next_go = from->next_go + 1;
            if (ret->next_go >= ret->params.nguesses)
-               ret->solved = 1; /* 'lose' so we show the pegs. */
+               ret->solved = -1; /* lose, meaning we show the pegs. */
        }
 
        return ret;
@@ -806,8 +976,8 @@ static game_state *execute_move(game_state *from, char *move)
 
 #define BORDER    0.5
 
-static void game_compute_size(game_params *params, int tilesize,
-                             int *x, int *y)
+static void game_compute_size(const game_params *params, int tilesize,
+                              int *x, int *y)
 {
     double hmul, vmul_c, vmul_g, vmul;
     int hintw = (params->npegs+1)/2;
@@ -834,7 +1004,7 @@ static void game_compute_size(game_params *params, int tilesize,
 }
 
 static void game_set_size(drawing *dr, game_drawstate *ds,
-                         game_params *params, int tilesize)
+                          const game_params *params, int tilesize)
 {
     int colh, guessh;
 
@@ -861,10 +1031,10 @@ static void game_set_size(drawing *dr, game_drawstate *ds,
 
     assert(ds->pegsz > 0);
     assert(!ds->blit_peg);             /* set_size is never called twice */
-    ds->blit_peg = blitter_new(dr, ds->pegsz, ds->pegsz);
+    ds->blit_peg = blitter_new(dr, ds->pegsz+2, ds->pegsz+2);
 }
 
-static float *game_colours(frontend *fe, game_state *state, int *ncolours)
+static float *game_colours(frontend *fe, int *ncolours)
 {
     float *ret = snewn(3 * NCOLOURS, float), max;
     int i;
@@ -876,19 +1046,19 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
     ret[COL_1 * 3 + 1] = 0.0F;
     ret[COL_1 * 3 + 2] = 0.0F;
 
-    /* yellow (toned down a bit due to pale grey background) */
-    ret[COL_2 * 3 + 0] = 0.7F;
-    ret[COL_2 * 3 + 1] = 0.7F;
+    /* yellow */
+    ret[COL_2 * 3 + 0] = 1.0F;
+    ret[COL_2 * 3 + 1] = 1.0F;
     ret[COL_2 * 3 + 2] = 0.0F;
 
-    /* green (also toned down) */
+    /* green */
     ret[COL_3 * 3 + 0] = 0.0F;
-    ret[COL_3 * 3 + 1] = 0.5F;
+    ret[COL_3 * 3 + 1] = 1.0F;
     ret[COL_3 * 3 + 2] = 0.0F;
 
     /* blue */
-    ret[COL_4 * 3 + 0] = 0.0F;
-    ret[COL_4 * 3 + 1] = 0.0F;
+    ret[COL_4 * 3 + 0] = 0.2F;
+    ret[COL_4 * 3 + 1] = 0.3F;
     ret[COL_4 * 3 + 2] = 1.0F;
 
     /* orange */
@@ -902,19 +1072,19 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
     ret[COL_6 * 3 + 2] = 0.7F;
 
     /* brown */
-    ret[COL_7 * 3 + 0] = 0.4F;
-    ret[COL_7 * 3 + 1] = 0.2F;
-    ret[COL_7 * 3 + 2] = 0.2F;
+    ret[COL_7 * 3 + 0] = 0.5F;
+    ret[COL_7 * 3 + 1] = 0.3F;
+    ret[COL_7 * 3 + 2] = 0.3F;
 
     /* light blue */
     ret[COL_8 * 3 + 0] = 0.4F;
-    ret[COL_8 * 3 + 1] = 0.7F;
+    ret[COL_8 * 3 + 1] = 0.8F;
     ret[COL_8 * 3 + 2] = 1.0F;
 
     /* light green */
-    ret[COL_9 * 3 + 0] = 0.5F;
-    ret[COL_9 * 3 + 1] = 0.8F;
-    ret[COL_9 * 3 + 2] = 0.5F;
+    ret[COL_9 * 3 + 0] = 0.7F;
+    ret[COL_9 * 3 + 1] = 1.0F;
+    ret[COL_9 * 3 + 2] = 0.7F;
 
     /* pink */
     ret[COL_10 * 3 + 0] = 1.0F;
@@ -960,15 +1130,15 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
 
     /* We also want to be able to tell the difference between BACKGROUND
      * and EMPTY, for similar distinguishing-hint reasons. */
-    ret[COL_EMPTY * 3 + 0] = ret[COL_BACKGROUND * 3 + 0] * 2.0 / 3.0;
-    ret[COL_EMPTY * 3 + 1] = ret[COL_BACKGROUND * 3 + 1] * 2.0 / 3.0;
-    ret[COL_EMPTY * 3 + 2] = ret[COL_BACKGROUND * 3 + 2] * 2.0 / 3.0;
+    ret[COL_EMPTY * 3 + 0] = ret[COL_BACKGROUND * 3 + 0] * 2.0F / 3.0F;
+    ret[COL_EMPTY * 3 + 1] = ret[COL_BACKGROUND * 3 + 1] * 2.0F / 3.0F;
+    ret[COL_EMPTY * 3 + 2] = ret[COL_BACKGROUND * 3 + 2] * 2.0F / 3.0F;
 
     *ncolours = NCOLOURS;
     return ret;
 }
 
-static game_drawstate *game_new_drawstate(drawing *dr, game_state *state)
+static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
 {
     struct game_drawstate *ds = snew(struct game_drawstate);
     int i;
@@ -1007,7 +1177,7 @@ static void game_free_drawstate(drawing *dr, game_drawstate *ds)
 }
 
 static void draw_peg(drawing *dr, game_drawstate *ds, int cx, int cy,
-                    int moving, int col)
+                    int moving, int labelled, int col)
 {
     /*
      * Some platforms antialias circles, which means we shouldn't
@@ -1022,9 +1192,18 @@ static void draw_peg(drawing *dr, game_drawstate *ds, int cx, int cy,
                   COL_BACKGROUND);
     if (PEGRAD > 0) {
         draw_circle(dr, cx+PEGRAD, cy+PEGRAD, PEGRAD,
-                   COL_EMPTY + col, COL_EMPTY + col);
+                   COL_EMPTY + col, (col ? COL_FRAME : COL_EMPTY));
     } else
         draw_rect(dr, cx, cy, PEGSZ, PEGSZ, COL_EMPTY + col);
+
+    if (labelled && col) {
+        char buf[2];
+        buf[0] = 'a'-1 + col;
+        buf[1] = '\0';
+        draw_text(dr, cx+PEGRAD, cy+PEGRAD, FONT_VARIABLE, PEGRAD,
+                  ALIGN_HCENTRE|ALIGN_VCENTRE, COL_FRAME, buf);
+    }
+
     draw_update(dr, cx-CGAP, cy-CGAP, PEGSZ+CGAP*2, PEGSZ+CGAP*2);
 }
 
@@ -1036,7 +1215,8 @@ static void draw_cursor(drawing *dr, game_drawstate *ds, int x, int y)
 }
 
 static void guess_redraw(drawing *dr, game_drawstate *ds, int guess,
-                         pegrow src, int *holds, int cur_col, int force)
+                         pegrow src, int *holds, int cur_col, int force,
+                         int labelled)
 {
     pegrow dest;
     int rowx, rowy, i, scol;
@@ -1058,8 +1238,11 @@ static void guess_redraw(drawing *dr, game_drawstate *ds, int guess,
             scol |= 0x1000;
         if (holds && holds[i])
             scol |= 0x2000;
+        if (labelled)
+            scol |= 0x4000;
         if ((dest->pegs[i] != scol) || force) {
-           draw_peg(dr, ds, rowx + PEGOFF * i, rowy, FALSE, scol &~ 0x3000);
+           draw_peg(dr, ds, rowx + PEGOFF * i, rowy, FALSE, labelled,
+                     scol &~ 0x7000);
             /*
              * Hold marker.
              */
@@ -1129,7 +1312,8 @@ static void hint_redraw(drawing *dr, game_drawstate *ds, int guess,
                 rowy += HINTOFF;
             }
             if (HINTRAD > 0) {
-                draw_circle(dr, rowx+HINTRAD, rowy+HINTRAD, HINTRAD, col, col);
+                draw_circle(dr, rowx+HINTRAD, rowy+HINTRAD, HINTRAD, col,
+                            (col == emptycol ? emptycol : COL_FRAME));
             } else {
                 draw_rect(dr, rowx, rowy, HINTSZ, HINTSZ, col);
             }
@@ -1156,14 +1340,14 @@ static void currmove_redraw(drawing *dr, game_drawstate *ds, int guess, int col)
     draw_update(dr, ox-off-1, oy, 2, PEGSZ);
 }
 
-static void game_redraw(drawing *dr, game_drawstate *ds, game_state *oldstate,
-                       game_state *state, int dir, game_ui *ui,
-                       float animtime, float flashtime)
+static void game_redraw(drawing *dr, game_drawstate *ds,
+                        const game_state *oldstate, const game_state *state,
+                        int dir, const game_ui *ui,
+                        float animtime, float flashtime)
 {
-    int i, new_move, last_go;
+    int i, new_move;
 
     new_move = (state->next_go != ds->next_go) || !ds->started;
-    last_go = (state->next_go == state->params.nguesses-1);
 
     if (!ds->started) {
       draw_rect(dr, 0, 0, ds->w, ds->h, COL_BACKGROUND);
@@ -1182,35 +1366,42 @@ static void game_redraw(drawing *dr, game_drawstate *ds, game_state *oldstate,
         int val = i+1;
         if (ui->display_cur && ui->colour_cur == i)
             val |= 0x1000;
+        if (ui->show_labels)
+            val |= 0x2000;
         if (ds->colours->pegs[i] != val) {
-           draw_peg(dr, ds, COL_X(i), COL_Y(i), FALSE, i+1);
+           draw_peg(dr, ds, COL_X(i), COL_Y(i), FALSE, ui->show_labels, i+1);
             if (val & 0x1000)
                 draw_cursor(dr, ds, COL_X(i), COL_Y(i));
             ds->colours->pegs[i] = val;
         }
     }
 
-    /* draw the guesses (so far) and the hints */
-    for (i = 0; i < state->params.nguesses; i++) {
-        if (state->next_go > i || state->solved) {
+    /* draw the guesses (so far) and the hints
+     * (in reverse order to avoid trampling holds, and postponing the
+     * next_go'th to not overrender the top of the circular cursor) */
+    for (i = state->params.nguesses - 1; i >= 0; i--) {
+        if (i < state->next_go || state->solved) {
             /* this info is stored in the game_state already */
-            guess_redraw(dr, ds, i, state->guesses[i], NULL, -1, 0);
+            guess_redraw(dr, ds, i, state->guesses[i], NULL, -1, 0,
+                         ui->show_labels);
             hint_redraw(dr, ds, i, state->guesses[i],
                         i == (state->next_go-1) ? 1 : 0, FALSE, FALSE);
-        } else if (state->next_go == i) {
-            /* this is the one we're on; the (incomplete) guess is
-             * stored in the game_ui. */
-            guess_redraw(dr, ds, i, ui->curr_pegs,
-                         ui->holds, ui->display_cur ? ui->peg_cur : -1, 0);
-            hint_redraw(dr, ds, i, NULL, 1,
-                        ui->display_cur && ui->peg_cur == state->params.npegs,
-                        ui->markable);
-        } else {
+        } else if (i > state->next_go) {
             /* we've not got here yet; it's blank. */
-            guess_redraw(dr, ds, i, NULL, NULL, -1, 0);
+            guess_redraw(dr, ds, i, NULL, NULL, -1, 0, ui->show_labels);
             hint_redraw(dr, ds, i, NULL, 0, FALSE, FALSE);
         }
     }
+    if (!state->solved) {
+       /* this is the one we're on; the (incomplete) guess is stored in
+        * the game_ui. */
+       guess_redraw(dr, ds, state->next_go, ui->curr_pegs,
+                    ui->holds, ui->display_cur ? ui->peg_cur : -1, 0,
+                    ui->show_labels);
+       hint_redraw(dr, ds, state->next_go, NULL, 1,
+                   ui->display_cur && ui->peg_cur == state->params.npegs,
+                   ui->markable);
+    }
 
     /* draw the 'current move' and 'able to mark' sign. */
     if (new_move)
@@ -1219,13 +1410,14 @@ static void game_redraw(drawing *dr, game_drawstate *ds, game_state *oldstate,
         currmove_redraw(dr, ds, state->next_go, COL_HOLD);
 
     /* draw the solution (or the big rectangle) */
-    if ((state->solved != ds->solved) || !ds->started) {
+    if ((!state->solved ^ !ds->solved) || !ds->started) {
         draw_rect(dr, SOLN_OX, SOLN_OY, SOLN_W, SOLN_H,
                   state->solved ? COL_BACKGROUND : COL_EMPTY);
         draw_update(dr, SOLN_OX, SOLN_OY, SOLN_W, SOLN_H);
     }
     if (state->solved)
-        guess_redraw(dr, ds, -1, state->solution, NULL, -1, !ds->solved);
+        guess_redraw(dr, ds, -1, state->solution, NULL, -1, !ds->solved,
+                     ui->show_labels);
     ds->solved = state->solved;
 
     ds->next_go = state->next_go;
@@ -1235,44 +1427,49 @@ static void game_redraw(drawing *dr, game_drawstate *ds, game_state *oldstate,
     if (ui->drag_col != 0) {
         int ox = ui->drag_x - (PEGSZ/2);
         int oy = ui->drag_y - (PEGSZ/2);
-        debug(("Saving to blitter at (%d,%d)", ox, oy));
-        blitter_save(dr, ds->blit_peg, ox, oy);
-        draw_peg(dr, ds, ox, oy, TRUE, ui->drag_col);
-
-        ds->blit_ox = ox; ds->blit_oy = oy;
+        ds->blit_ox = ox - 1; ds->blit_oy = oy - 1;
+        debug(("Saving to blitter at (%d,%d)", ds->blit_ox, ds->blit_oy));
+        blitter_save(dr, ds->blit_peg, ds->blit_ox, ds->blit_oy);
+        draw_peg(dr, ds, ox, oy, TRUE, ui->show_labels, ui->drag_col);
     }
     ds->drag_col = ui->drag_col;
 
     ds->started = 1;
 }
 
-static float game_anim_length(game_state *oldstate, game_state *newstate,
-                             int dir, game_ui *ui)
+static float game_anim_length(const game_state *oldstate,
+                              const game_state *newstate, int dir, game_ui *ui)
 {
     return 0.0F;
 }
 
-static float game_flash_length(game_state *oldstate, game_state *newstate,
-                              int dir, game_ui *ui)
+static float game_flash_length(const game_state *oldstate,
+                               const game_state *newstate, int dir, game_ui *ui)
 {
     return 0.0F;
 }
 
-static int game_wants_statusbar(void)
+static int game_status(const game_state *state)
 {
-    return FALSE;
+    /*
+     * We return nonzero whenever the solution has been revealed, even
+     * (on spoiler grounds) if it wasn't guessed correctly. The
+     * correct return value from this function is already in
+     * state->solved.
+     */
+    return state->solved;
 }
 
-static int game_timing_state(game_state *state, game_ui *ui)
+static int game_timing_state(const game_state *state, game_ui *ui)
 {
     return TRUE;
 }
 
-static void game_print_size(game_params *params, float *x, float *y)
+static void game_print_size(const game_params *params, float *x, float *y)
 {
 }
 
-static void game_print(drawing *dr, game_state *state, int tilesize)
+static void game_print(drawing *dr, const game_state *state, int tilesize)
 {
 }
 
@@ -1281,7 +1478,7 @@ static void game_print(drawing *dr, game_state *state, int tilesize)
 #endif
 
 const struct game thegame = {
-    "Guess", "games.guess",
+    "Guess", "games.guess", "guess",
     default_params,
     game_fetch_preset,
     decode_params,
@@ -1296,7 +1493,7 @@ const struct game thegame = {
     dup_game,
     free_game,
     TRUE, solve_game,
-    FALSE, game_text_format,
+    FALSE, game_can_format_as_text_now, game_text_format,
     new_ui,
     free_ui,
     encode_ui,
@@ -1311,8 +1508,9 @@ const struct game thegame = {
     game_redraw,
     game_anim_length,
     game_flash_length,
+    game_status,
     FALSE, FALSE, game_print_size, game_print,
-    game_wants_statusbar,
+    FALSE,                            /* wants_statusbar */
     FALSE, game_timing_state,
     0,                                /* flags */
 };