fix random seed initialization

battleships.c

@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
+#include <time.h>
 
 enum {
   BOARD_SIZE = 10,
@@ -60,6 +61,8 @@ enum target {
 enum target check_hit(struct state state, struct position hit);
 
 int main(void) {
+    srand(time(NULL));
+
     struct state state = generate_state();
 
     while (!state.game_over) {