HW3: refactor complete

chess_paths/chess_paths.c

@@ -17,6 +17,8 @@
 #include <stdio.h>
 #include <stdbool.h>
 
+#define DEBUG 0
+
 #if DEBUG
 char* NAMES[] = { "KING", "QUEEN", "ROOK", "BISHOP", "KNIGHT", "PAWN" };
 
@@ -61,7 +63,7 @@ inline unsigned long table_hash(const struct chessboard* c, unsigned col,
         unsigned row) {
     return (value_at(c, col, row) ^ (('C'|'a') << 24 | ('r'|'z') << 16 |
                 ('a'|'n') << 8 | ('i'|'g'|'a')))
-            % table_total_size(c);
+        % table_total_size(c);
 }
 
 visit_table* table_new(const struct chessboard* c) {
@@ -154,7 +156,13 @@ void search_status_init(struct search_status* s, struct piece_position* p,
  */
 
 void consider(struct search_status* s, unsigned column, unsigned row) {
-    if (s->better(s, column, row)) {
+    const bool b = s->better(s, column, row);
+
+#if DEBUG
+    printf("consider c=%u r=%u better=%u\n", column, row, b);
+#endif
+
+    if (b) {
         s->found = true;
         s->column = column;
         s->row = row;
@@ -255,9 +263,6 @@ void consider_positions(struct search_status* s, struct piece_position* p) {
         case BISHOP: bishop_positions(s, p); break;
         case QUEEN: queen_positions(s, p); break;
     }
-#if DEBUG
-    print_poss(poss, p);
-#endif
 }
 
 unsigned int path_len(const struct chessboard* c,
@@ -266,7 +271,6 @@ unsigned int path_len(const struct chessboard* c,
         visit_table* table) {
 
     unsigned int hops = 0;
-    bool has_next = true;
 
 #if DEBUG
     printf("board r=%u c=%u\n", rows(c), columns(c));
@@ -275,12 +279,26 @@ unsigned int path_len(const struct chessboard* c,
     struct search_status status;
     search_status_init(&status, p, better, c, table);
 
-    while (has_next) {
+    while (true) {
+        status.found = false;
         consider_positions(&status, p);
-        has_next = status.found;
+
+#if DEBUG
+        printf("consideration c=%u r=%u\n", status.column, status.row);
+        print_p_position(p);
+#endif
+
+        if (status.column == p->column && status.row == p->row) {
+            break;
+        }
+
         p->column = status.column;
         p->row = status.row;
 
+        if (status.table != NULL) {
+            table_visit(c, table, p->column, p->row);
+        }
+
 #if DEBUG
         print_p_position(p);
 #endif
@@ -288,106 +306,43 @@ unsigned int path_len(const struct chessboard* c,
         hops++;
     }
 
-    return hops - 1;
+    return hops;
 }
 
 
 bool better_inc(struct search_status* s, unsigned column, unsigned row) {
-    return value_at(s->chessboard, s->column, s->row) >
+    return value_at(s->chessboard, column, row) >
-        value_at(s->chessboard, column, row);
+        value_at(s->chessboard, s->column, s->row);
 }
 
 bool better_dec(struct search_status* s, unsigned column, unsigned row) {
-    return value_at(s->chessboard, s->column, s->row) <
+    return value_at(s->chessboard, column, row) <
-        value_at(s->chessboard, column, row);
+        value_at(s->chessboard, s->column, s->row);
 }
 
 bool better_simple(struct search_status* s, unsigned column, unsigned row) {
     return !table_visited(s->chessboard, s->table, column, row) &&
-        (!s->found || (value_at(s->chessboard, s->column, s->row) >
+        (!s->found || value_at(s->chessboard, column, row) >
-        value_at(s->chessboard, column, row)));
+         value_at(s->chessboard, s->column, s->row));
 }
 
 unsigned int increasing_path_len(const struct chessboard* c,
         struct piece_position* p) {
-
+    return path_len(c, p, better_inc, NULL);
 }
 
 unsigned int decreasing_path_len(const struct chessboard* c,
         struct piece_position* p) {
-
+    return path_len(c, p, better_dec, NULL);
-    unsigned int hops = 0;
-    bool has_next = true;
-
-#if DEBUG
-    puts("decreasing");
-    printf("board r=%u c=%u\n", rows(c), columns(c));
-#endif
-
-    struct search_status status;
-    search_status_init(&status, p, better_inc, c, NULL);
-
-    while (has_next) {
-        consider_positions(&status, p);
-        has_next = status.found;
-        p->column = status.column;
-        p->row = status.row;
-
-#if DEBUG
-        print_p_position(p);
-#endif
-
-        hops++;
-    }
-
-    return hops - 1;
 }
+
 unsigned int simple_path_len(const struct chessboard* c,
         struct piece_position* p) {
-
     visit_table* v = table_new(c);
     table_visit(c, v, p->column, p->row);
 
-#if DEBUG
+    unsigned int len = path_len(c, p, better_simple, v);
-    print_visited(c, v);
-#endif
-
-    bool has_next = true;
-    unsigned hops = 0;
-
-    while(has_next) {
-        struct position* poss = get_positions(c, p);
-        has_next = false;
-        unsigned int base_v = 0, next_v;
-
-#if DEBUG
-        puts("simple");
-        print_p_position(p);
-#endif
-
-        while(poss != NULL) {
-            if (!table_visited(c, v, poss->column, poss->row)) {
-                next_v = value_at(c, poss->column, poss->row);
-                if (!has_next || next_v > base_v) {
-                    has_next = true;
-                    p->row = poss->row;
-                    p->column = poss->column;
-                    base_v = next_v;
-                }
-            }
-            struct position* del = poss;
-            poss = poss->next;
-            free(del);
-        }
-
-        table_visit(c, v, p->column, p->row);
-#if DEBUG
-        print_visited(c, v);
-#endif
-        hops++;
-    }
 
     table_destroy(c, v);
-    return hops - 1;
+    return len;
 }
-