Perfect square

subject ：

Give you an integer n , return And for n The minimum number of complete squares of .

Complete square It's an integer , Its value is equal to the square of another integer ; let me put it another way , Its value is equal to the product of the self multiplication of an integer . for example ,1、4、9 and 16 They're all perfect squares , and 3 and 11 No .

Example 1：

Input ：n = 12
Output ：3
explain ：12 = 4 + 4 + 4

Example 2：

Input ：n = 13
Output ：2
explain ：13 = 4 + 9

Code ：

class Solution {
    public int numSquares(int n) {
       int max = Integer.MAX_VALUE;
       int[] dp = new int[n+1];
       for(int j = 0; j <= n; j++){
           dp[j] = max;
       }
       dp[0] = 0;
       for(int i = 0; i * i <= n; i++){
           for(int j = i * i; j <= n; j++){
               if(dp[j - i * i] != max){
                   dp[j] = Math.min(dp[j], dp[j- i *i] +1);
               }
           }
       }
       return dp[n];
    }
}