1 class Solution {
 2 public:
 3     void replaceSpace(char *str,int len) {
 4         int cnt = 0;
 5         for (int i = 0; i < len; i++) {
 6             if (str[i] == ' ') cnt++;
 7         }
 8         int idx = len + cnt * 2 - 1;
 9         for (int i = len - 1; i >= 0; i--) {
10             if (str[i] == ' ') {
11                 str[idx--] = '0';
12                 str[idx--] = '2';
13                 str[idx--] = '%';
14             } else {
15                 str[idx--] = str[i];
16             }
17         }
18     }
19 };