LeetCode 面试题 16.21. 交换和

原题目： https://leetcode-cn.com/problems/sum-swap-lcci/

 

思路：

交换的两个数之差是（sum1 - sum2）的一半。注意如果（sum1 - sum2）是奇数就不会有解

代码：

class Solution {
public:
    vector findSwapValues(vector& array1, vector& array2) {
        long sum1 = accumulate(array1.begin(),array1.end(),0);
        long sum2 = accumulate(array2.begin(),array2.end(),0);
        long diff = sum1 - sum2;
        vector a;
        if(diff%2){
            return a;
        }
        map m;    
        diff = diff/2;
        for(int i=0;i0 && array1[i] ==array1[i-1]){
                continue;
            }
            int b = array1[i] - diff;
            if(m[b] == 1){
                a.push_back(array1[i]);
                a.push_back(b);
                return a;
            }
        }
        return a;
    }
};