题解 100% AC

#include <bits/stdc++.h>
using namespace std;
int numSquares(int n) {
    vector<int> dp(n + 1, INT_MAX);
    dp[0] = 0;
    for (int i = 1; i <= n; ++i) for (int j = 1; j * j <= i; ++j) dp[i] = min(dp[i], dp[i - j * j] + 1);
    return dp[n];
}
int main() {
    int n;
    cin >> n;
    cout << numSquares(n) << endl;
    return 0;
}