func_code_string: #include <bits/stdc++.h>   using namespace std;   char s[131100];   int cal(int l, int r, char t) {     int cnt = 0;     for (int i = l; i <= r; i++) {       if (s[i] != t) cnt++;     }     return cnt;   }   int dfs(int l, int r, char t) {     if (l == r) return cal(l, r, t);     int ret = 1e9;     int mid = (l + r) >> 1;     ret = min(ret, dfs(l, mid, t + 1) + cal(mid + 1, r, t));     ret = min(ret, dfs(mid + 1, r, t + 1) + cal(l, mid, t));     return ret;   }   int main() {     int _;     scanf( %d , &_);     while (_--) {       int n;       scanf( %d , &n);       scanf( %s , s);       char temp =  a ;       printf( %d n , dfs(0, n - 1, temp));     }     return 0;   }   