Envío 2187

Código

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

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

  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;
}