Envío 4011

Código

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

#define endl '\n'
#define ll long long
#define sz(x) int(x.size())
#define dbg(x) cout << #x << " = " << x << endl

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    string s;
    int k;
    cin >> s >> k;
    int n = sz(s);

    int j, dif, ans, fre[26];
    memset(fre, 0, sizeof fre);
    dif = ans = 0;
    j = -1;
    for (int i = 0; i < n; ++i) {
        while (++j < n) {
            dif += !fre[s[j] - 'a'];
            fre[s[j] - 'a']++;
            if (dif > k) break;
            ans = max(ans, j - i + 1);
        }
        if (j == n) break;
        fre[s[i] - 'a']--;
        dif -= !fre[s[i] - 'a'];
    }
    cout << ans << endl;
    return 0;
}