Giới thiệu
include <iostream>
include <vector>
include <string>
using namespace std;
int main() {
int N, Q;
cin >> N >> Q;
string S;
cin >> S;
vector<vector\<int>> freq(N + 1, vector<int>(26, 0));
for (int i = 0; i < N; ++i) {
for (int j = 0; j < 26; ++j) {
freq[i + 1][j] = freq[i][j];
}
freq[i + 1][S[i] - 'a']++;
}
// Xử lý các truy vấn
for (int i = 0; i < Q; ++i) {
int L, R;
char C;
cin >> L >> R >> C;
int count = freq[R][C - 'a'] - freq[L - 1][C - 'a'];
cout << count << endl;
}
return 0;
}