动态规划 完全平方数

Posted 2021-01-08 tiandiou

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

Example 1:

Input: n = 12
Output: 3 
Explanation: 12 = 4 + 4 + 4.

Example 2:

Input: n = 13
Output: 2
Explanation: 13 = 4 + 9.

public static int numSquares(int n) {
        int[] dp = new int[n+1];
        for(int i = 1; i <= n ;i++)
            dp[i] = Integer.MAX_VALUE;
        for(int i = 0; i <= n; i++)
            for(int j = 1 ;i+j*j <= n;j++)
                dp[i+j*j]= dp[i+j*j]>dp[i]+1 ? dp[i]+1 : dp[i+j*j];　　
        return dp[n];
    }