题解 | 小牛的作业

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

int main() {
    string s, t;
    cin >> s >> t;
    int n = (int)s.size(), m = (int)t.size();
    if (n < m) { cout << -1 << '\n'; return 0; }

    int cs[26] = {0}, ct[26] = {0};
    for (char c : s) cs[c - 'a']++;
    for (char c : t) ct[c - 'a']++;

    long long S = 0;                 // 过量
    for (int i = 0; i < 26; ++i) S += max(0, cs[i] - ct[i]);

    long long D = n - m;             // 必须删除的个数
    long long ans = D + llabs(D - S);
    cout << ans << '\n';
    return 0;
}