题解 | 舞萌时间到！

#include <bits/stdc++.h>
#include <numeric>
using namespace std;

int main() {
    string s;
    int p;
    cin >> s >> p;
    vector<int> vec;
    for (int i = 0; i < s.size(); i++) {
        switch (s[i]) {
            case 'P':
                vec.push_back(3);
                break;
            case 'p':
                vec.push_back(2);
                break;
            case 'G':
                vec.push_back(1);
                break;
            default:
                vec.push_back(0);
        }
    }
    vector<int> prefix(vec.size() + 1, 0);
    partial_sum(vec.begin(), vec.end(), prefix.begin() + 1);

    while (p--) {
        int a, b;
        cin >> a >> b; 
        if (a < 1 || b > vec.size() || a > b) {
            cout << 0 << endl;
            continue;
        }
        int sum = prefix[b] - prefix[a - 1];
        cout << sum << endl;
    }
    return 0;
}