Implement the helper functions needed to list the playble shots

[Project_algorithmic_C.git] / lib / othello.c

diff --git a/lib/othello.c b/lib/othello.c
index e1290b4f3f39e6455e8711e784404827552c77aa..5d9970c6941a0942d8e948a90541a0a55a06fdbd 100644 (file)
--- a/lib/othello.c
+++ b/lib/othello.c
@@ -180,25 +180,34 @@ unsigned int eval_winner(unsigned int nb_white, unsigned int nb_black) {
     }
 }
 
-static unsigned int reverse_one_direction(int y, int x, int direction, unsigned int current_player, unsigned int pawn_array[board_size][board_size]) {
-    unsigned int nb_pawns_reserved = 0;
+static unsigned int count_pawn_to_reverse_one_direction(int y, int x, int direction, unsigned int current_player, unsigned int pawn_array[board_size][board_size]) {
+    unsigned int nb_pawns_reversed = 0;
     int moving_y = y, moving_x = x;
 
-    /* count for pawn to reverse in the chosen direction */
+    /* count the pawns to reverse in the chosen direction */
     direction_to_coordinates(direction, &moving_y, &moving_x);
     while (true) {
         if (!is_valid_coordinates(moving_y, moving_x) || is_box_type(moving_y, moving_x, pawn_array, empty)) {
-                return 0;
+            return 0;
         }
         if (is_box_type(moving_y, moving_x, pawn_array, current_player)) {
             break;
         }
-        nb_pawns_reserved++;
+        nb_pawns_reversed++;
         direction_to_coordinates(direction, &moving_y, &moving_x);
     }
+    return nb_pawns_reversed;
+}
+
+/* revert the pawns if needed in one direction */ 
+static unsigned int reverse_one_direction(int y, int x, int direction, unsigned int current_player, unsigned int pawn_array[board_size][board_size], bool dry_run) {
+    unsigned int nb_pawns_reversed = 0;
+    int moving_y = y, moving_x = x;
+
+    nb_pawns_reversed = count_pawn_to_reverse_one_direction(moving_y, moving_x, direction, current_player, pawn_array);
 
-    /* now reverse the needed panws */
-    if (nb_pawns_reserved > 0) {
+    /* now reverse the needed pawns */
+    if (nb_pawns_reversed > 0 && !dry_run) {
         moving_y = y, moving_x = x;
         direction_to_coordinates(direction, &moving_y, &moving_x);
         while (!is_box_type(moving_y, moving_x, pawn_array, current_player)) {
@@ -206,25 +215,41 @@ static unsigned int reverse_one_direction(int y, int x, int direction, unsigned
             direction_to_coordinates(direction, &moving_y, &moving_x);
         }
     }
-    return nb_pawns_reserved;
+    return nb_pawns_reversed;
+}
+
+/* loop optimized version of valid_shot changing nothing to the pawns 2D array */
+static bool is_legal_shot(int y, int x, unsigned int current_player, unsigned int pawn_array[board_size][board_size]) {
+    unsigned int nb_pawns_reversed = 0;
+    
+    if (!is_valid_coordinates(y, x) || !is_box_type(y, x, pawn_array, empty)) {
+        return false;
+    }
+    
+    for (unsigned int direction = north; direction <= north_west; direction++) {
+        nb_pawns_reversed += reverse_one_direction(y, x, direction, current_player, pawn_array, true);
+        if (nb_pawns_reversed > 0) {
+            return true;
+        }
+    }
 }
 
 /* play the shot if legal and flip or reverse the necessary pawns */
 unsigned int valid_shot(int y, int x, unsigned int current_player, unsigned int pawn_array[board_size][board_size]) {
-    unsigned int nb_pawns_reserved = 0;
+    unsigned int nb_pawns_reversed = 0;
 
     if (!is_valid_coordinates(y, x) || !is_box_type(y, x, pawn_array, empty)) {
         return 0;
     }
 
     for (unsigned int direction = north; direction <= north_west; direction++) {
-        nb_pawns_reserved += reverse_one_direction(y, x, direction, current_player, pawn_array);
+        nb_pawns_reversed += reverse_one_direction(y, x, direction, current_player, pawn_array, false);
     }
     
-    if (nb_pawns_reserved == 0) {
+    if (nb_pawns_reversed == 0) {
         return 0;
     }
 
     set_pawn(y, x, current_player, pawn_array);
-    return nb_pawns_reserved;
+    return nb_pawns_reversed;
 }