Back To School '18: Letter Frequency

    1#include <bits/stdc++.h>
    2using namespace std;
    3 
    4int main(){
    5    ios::sync_with_stdio(0); cin.tie(0);
    6    string s;
    7    getline(cin, s);
    8    vector<vector<int>> f(26, vector<int>(s.size() + 1));
    9    for(int i = 0; i < s.size(); i++){
    10        char c = s[i];
    11        if(c == ' ') continue;
    12        int pos = c - 'a';
    13        f[pos][i + 1]++;
    14    }
    15    for(int i = 0; i < 26; i++){
    16        for(int j = 1; j < f[i].size(); j++){
    17            f[i][j] += f[i][j - 1];
    18        }
    19    }
    20    int q;
    21    cin >> q;
    22    while(q--){
    23        int x, y; cin >> x >> y;
    24        char c; cin >> c;
    25        int pos = c - 'a';
    26        int ans = f[pos][y] - f[pos][x - 1];
    27        cout << ans << '\n';
    28    }
    29    return 0;
    30}