Envío 2186

Código

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

int main() {
  string s;
  cin >> s;
  int k;
  cin >> k;

  if (k == 26) {
    cout << s.size() << endl;
  } else {
    int start = 0;
    unordered_map<int, int> m;
    int min_size = INT_MAX;
    for (int i = 0; i < s.size(); i++) {
      char c = s[i];
      m[c]++;
      if (m.size() == k) {
        min_size = min(min_size, i - start + 1);
        while (m.size() == k) {
          char st = s[start++];
          m[st]--;
          if (m[st] == 0) {
            m.erase(st);
          } else {
            min_size = min(min_size, i - start + 1);
          }
        }
      }
    }
    if (min_size == INT_MAX)
      cout << -1 << endl;
    else
      cout << min_size << endl;
  }
}