Leimasin

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const int N = 1010101;
char c[N];

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);

  int n, m, k;
  cin >> n >> m >> k;

  string stamp;
  cin >> stamp;

  vector<int> v(k);
  for (int i = 0; i < k; ++i) cin >> v[i];
  reverse(v.begin(), v.end());

  // vector<char> c(n);
  for (int i = 0; i <= n; ++i) c[i] = '.';

  set<int> s;
  for (int i = 1; i <= n; ++i) s.insert(i);

  for (int x : v) {

    if (m < 100) {
      for (int i = 0; i < m; ++i) {
        if (i + x > n) break;
        if (c[i + x] == '.') c[i + x] = stamp[i];
      }
      continue;
    }

    vector<int> r;
    auto it = s.lower_bound(x);
    while (it != s.end() && *it - x < m) {
      r.push_back(*it);
      ++it;
    }

    for (int rx : r) {
      s.erase(rx);
      c[rx] = stamp[rx - x];
    }
  }

  for (int i = 1; i <= n; ++i) cout << c[i];
  cout << endl;
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 2, 3

Verdict: ACCEPTED

Test 6

Group: 2, 3

Verdict: ACCEPTED

Test 7

Group: 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 3

Verdict: ACCEPTED

Test 10

Group: 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED