Perfect Squares

class Solution {
public:
    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];
    }
};