【AtCoder】ABC 449 C - Comfortable Distance

1.#include <bits/stdc++.h>
2.using namespace std;
3. 
4.#define all(x) (x).begin(), (x).end()
5.#define rep(i, start, end) for (auto i = (start); (i) < (end); (i)++)
6. 
7.using ll = long long;
8. 
9.// ======================================== //
10. 
11.int main()
12.{
13.    int N, L, R;
14.    string S;
15.    cin >> N >> L >> R >> S;
16. 
17.    vector<vector<int>> pos(26);
18.    rep(i, 0, N)
19.    {
20.        pos[S[i] - 'a'].push_back(i);
21.    }
22. 
23.    ll ans = 0;
24.    rep(i, 0, N)
25.    {
26.        int c = S[i] - 'a';
27. 
28.        int l = i + L;
29.        int r = i + R;
30. 
31.        auto itr_l = lower_bound(all(pos[c]), l);
32.        auto itr_r = upper_bound(all(pos[c]), r);
33. 
34.        ans += (itr_r - itr_l);
35.    }
36. 
37.    cout << ans << endl;
38. 
39.    return 0;
40.}