shithub: puzzles

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Fix an instance generation hang in Signpost.

Also expand the set of permissible parameters (add 1xN, Nx1 and 2x2).

--- a/signpost.c

+++ b/signpost.c

@@ -422,11 +422,12 @@

 static char *validate_params(const game_params *params, int full)

 {

-    if (params->w < 2 || params->h < 2)

-	return "Width and height must both be at least two";

-    if (params->w == 2 && params->h == 2)   /* leads to generation hang */

-	return "Width and height cannot both be two";

-

+    if (params->w < 1) return "Width must be at least one";

+    if (params->h < 1) return "Height must be at least one";

+    if (full && params->w == 1 && params->h == 1)

+	/* The UI doesn't let us move these from unsolved to solved,

+	 * so we disallow generating (but not playing) them. */

+	return "Width and height cannot both be one";

     return NULL;

 }

@@ -623,6 +624,7 @@

     state->dirs[taili] = 0;

     nfilled = 2;

+    assert(state->n > 1);

     while (nfilled < state->n) {

         /* Try and expand _from_ headi; keep going if there's only one

@@ -638,6 +640,8 @@

             an = cell_adj(state, headi, aidx, adir);

         } while (an == 1);

+	if (nfilled == state->n) break;

+

         /* Try and expand _to_ taili; keep going if there's only one

          * place to go to. */

         an = cell_adj(state, taili, aidx, adir);

@@ -800,6 +804,9 @@

     game_state *state = blank_game(params->w, params->h);

     char *ret;

     int headi, taili;

+

+    /* this shouldn't happen (validate_params), but let's play it safe */

+    if (params->w == 1 && params->h == 1) return dupstr("1a");

 generate:

     blank_game_into(state);