[LeetCode] Perfect Squares

Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n.

For example, given n = 12, return 3 because 12 = 4 + 4 + 4; given n = 13, return 2 because 13 = 4 + 9.

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];
    }
};