problem:https://leetcode.com/problems/perfect-squares

        数字类dp。查找当前数字减去一个平方数对应的最小拆分次数。

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];
    }
};