# LeetCode - 0888. Fair Candy Swap
### 題目網址：https://leetcode.com/problems/fair-candy-swap/
###### tags: `LeetCode` `Easy` `二分搜尋法（Binary Search）`

/*
    -LeetCode format-
    Problem: 888. Fair Candy Swap
    Difficulty: Easy
    
    by Inversionpeter
*/



class Solution {
public:
    vector<int> fairCandySwap(vector<int>& A, vector<int>& B) {
        int sumA = accumulate(A.begin(), A.end(), 0), sumB = accumulate(B.begin(), B.end(), 0), buffer;
        vector <int>::iterator iter;
        sort(A.begin(), A.end());
        for (int i = 0; i != B.size(); ++i) {
            buffer = (sumA - sumB + (B[i] << 1)) >> 1;
            iter = lower_bound(A.begin(), A.end(), buffer);
            if (iter != A.end() && *iter == buffer)
                return { buffer, B[i] };
        }
        return { -1, -1 };
    }
};