func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 200005;   const char c[3][4] = { RGB ,  GBR ,  BRG };   int sum[3][N];   char s[N];   int main() {     int n, k, T;     scanf( %d , &T);     while (T--) {       scanf( %d%d , &n, &k);       sum[0][0] = sum[1][0] = sum[2][0] = 0;       scanf( %s , s);       if (k == 1) {         printf( 0 n );         continue;       }       for (int i = 0; i < 3; i++) {         for (int j = 0; j < n; j++) {           if (s[j] != c[i][j % 3]) {             sum[i][j + 1] = sum[i][j] + 1;           } else {             sum[i][j + 1] = sum[i][j];           }         }       }       int ans = N;       for (int p = 0; p < 3; p++) {         for (int i = 1; i + k - 1 <= n; i++) {           int j = i + k - 1;           ans = min(ans, sum[p][j] - sum[p][i - 1]);         }       }       printf( %d n , ans);     }     return 0;   }   