1 files changed, 122 insertions, 0 deletions
diff --git a/apps/plugins/puzzles/latin.h b/apps/plugins/puzzles/latin.h
new file mode 100644
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--- /dev/null
+++ b/apps/plugins/puzzles/latin.h
@@ -0,0 +1,122 @@
+#ifndef LATIN_H
+#define LATIN_H
+
+#include "puzzles.h"
+
+typedef unsigned char digit;
+
+/* --- Solver structures, definitions --- */
+
+#ifdef STANDALONE_SOLVER
+extern int solver_show_working, solver_recurse_depth;
+#endif
+
+struct latin_solver {
+  int o;                /* order of latin square */
+  unsigned char *cube;  /* o^3, indexed by x, y, and digit:
+                           TRUE in that position indicates a possibility */
+  digit *grid;          /* o^2, indexed by x and y: for final deductions */
+
+  unsigned char *row;   /* o^2: row[y*cr+n-1] TRUE if n is in row y */
+  unsigned char *col;   /* o^2: col[x*cr+n-1] TRUE if n is in col x */
+
+#ifdef STANDALONE_SOLVER
+  char **names;         /* o: names[n-1] gives name of 'digit' n */
+#endif
+};
+#define cubepos(x,y,n) (((x)*solver->o+(y))*solver->o+(n)-1)
+#define cube(x,y,n) (solver->cube[cubepos(x,y,n)])
+
+#define gridpos(x,y) ((y)*solver->o+(x))
+#define grid(x,y) (solver->grid[gridpos(x,y)])
+
+
+/* --- Solver individual strategies --- */
+
+/* Place a value at a specific location. */
+void latin_solver_place(struct latin_solver *solver, int x, int y, int n);
+
+/* Positional elimination. */
+int latin_solver_elim(struct latin_solver *solver, int start, int step
+#ifdef STANDALONE_SOLVER
+                      , char *fmt, ...
+#endif
+                      );
+
+struct latin_solver_scratch; /* private to latin.c */
+/* Set elimination */
+int latin_solver_set(struct latin_solver *solver,
+                     struct latin_solver_scratch *scratch,
+                     int start, int step1, int step2
+#ifdef STANDALONE_SOLVER
+                     , char *fmt, ...
+#endif
+                     );
+
+/* Forcing chains */
+int latin_solver_forcing(struct latin_solver *solver,
+                         struct latin_solver_scratch *scratch);
+
+
+/* --- Solver allocation --- */
+
+/* Fills in (and allocates members for) a latin_solver struct.
+ * Will allocate members of snew, but not snew itself
+ * (allowing 'struct latin_solver' to be the first element in a larger
+ * struct, for example). */
+void latin_solver_alloc(struct latin_solver *solver, digit *grid, int o);
+void latin_solver_free(struct latin_solver *solver);
+
+/* Allocates scratch space (for _set and _forcing) */
+struct latin_solver_scratch *
+  latin_solver_new_scratch(struct latin_solver *solver);
+void latin_solver_free_scratch(struct latin_solver_scratch *scratch);
+
+
+/* --- Solver guts --- */
+
+/* Looped positional elimination */
+int latin_solver_diff_simple(struct latin_solver *solver);
+
+/* Looped set elimination; *extreme is set if it used
+ * the more difficult single-number elimination. */
+int latin_solver_diff_set(struct latin_solver *solver,
+                          struct latin_solver_scratch *scratch,
+                          int extreme);
+
+typedef int (*usersolver_t)(struct latin_solver *solver, void *ctx);
+typedef void *(*ctxnew_t)(void *ctx);
+typedef void (*ctxfree_t)(void *ctx);
+
+/* Individual puzzles should use their enumerations for their
+ * own difficulty levels, ensuring they don't clash with these. */
+enum { diff_impossible = 10, diff_ambiguous, diff_unfinished };
+
+/* Externally callable function that allocates and frees a latin_solver */
+int latin_solver(digit *grid, int o, int maxdiff,
+		 int diff_simple, int diff_set_0, int diff_set_1,
+		 int diff_forcing, int diff_recursive,
+		 usersolver_t const *usersolvers, void *ctx,
+		 ctxnew_t ctxnew, ctxfree_t ctxfree);
+
+/* Version you can call if you want to alloc and free latin_solver yourself */
+int latin_solver_main(struct latin_solver *solver, int maxdiff,
+		      int diff_simple, int diff_set_0, int diff_set_1,
+		      int diff_forcing, int diff_recursive,
+		      usersolver_t const *usersolvers, void *ctx,
+		      ctxnew_t ctxnew, ctxfree_t ctxfree);
+
+void latin_solver_debug(unsigned char *cube, int o);
+
+/* --- Generation and checking --- */
+
+digit *latin_generate(int o, random_state *rs);
+
+/* The order of the latin rectangle is max(w,h). */
+digit *latin_generate_rect(int w, int h, random_state *rs);
+
+int latin_check(digit *sq, int order); /* !0 => not a latin square */
+
+void latin_debug(digit *sq, int order);
+
+#endif