第四篇 Flip Game II

 1 public class Solution {
 2    public boolean canWin(String s) {
 3         if (s == null || s.length() <= 1) {
 4             return false;
 5         }
 6         ArrayList<String> validMoves = getValidMoves(s);
 7         if (validMoves.isEmpty()) {
 8             return false;
 9         }
10         for (String str : validMoves) {
11             if (!canWin(str)) {
12                 return true;
13             }
14         }
15         return false;
16     }
17     
18     private ArrayList<String> getValidMoves(String s) {
19         ArrayList<String> result = new ArrayList();
20         for (int i = 0; i < s.length() - 1; i++) {
21             if (s.charAt(i) == ‘+‘ && s.charAt(i + 1) == ‘+‘) {
22                 char[] tmp = s.toCharArray();
23                 tmp[i] = ‘-‘;
24                 tmp[i + 1] = ‘-‘;
25                 result.add(new String(tmp));
26             }
27         }
28         return result;
29     }
30 }