f 函数的返回值小于等于 min(n,m)。

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int f(string x, string y) {
    int m = x.size();
    int n = y.size();
    vector<vector<int>> v(m+1, vector<int>(n+1, 0));
    for (int i = 1; i <= m; i++) {
        for (int j = 1; j <= n; j++) {
            if (x[i-1] == y[j-1]) {
                v[i][j] = v[i-1][j-1] + 1;
            } else {
                v[i][j] = max(v[i-1][j], v[i][j-1]);
            }
        }
    }
    return v[m][n];
}

bool g(string x, string y) {
    if (x.size() != y.size()) {
        return false;
    }
    return f(x + x, y) == y.size();
}

int main() {
    string x, y;
    cin >> x >> y;
    cout << g(x, y) << endl;
    return 0;
}