343. Integer Break

Given a positive integer n, break it into the sum of at least two positive integers and maximize the product of those integers. Return the maximum product you can get.

For example, given n = 2, return 1 (2 = 1 + 1); given n = 10, return 36 (10 = 3 + 3 + 4).

Note: You may assume that n is not less than 2 and not larger than 58.

Credits:

Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

发现把数尽可能的分解成3的加和，所得的乘积大。

class Solution {
public:
int integerBreak(int n) {
unsigned int i=1;
if(n==2) return 1;
if(n==3) return 2;
while(3*i<n)
i++;
if(n==3*i) return pow(3,i);
if(n-(3*(i-1))==1) return 4*pow(3,i-2);
if(n-3*(i-1)==2) return 2*pow(3,i-1);

}
};