Exchange One Box Each to Equalize Two Candy Totals

### Problem Each value in `aliceSizes` or `bobSizes` is the candy count in one box owned by that person. Exchange exactly one box from each person so their new total candy counts are equal. Return `[Alice_box_size,Bob_box_size]`. At least one valid exchange exists; when several work, return any one. ```cpp class Solution { public: vector<int> fairCandySwap(vector<int>& aliceSizes, vector<int>& bobSizes); }; ``` ### Examples **Example 1:** ```text Input: aliceSizes = [1,4], bobSizes = [2,5] Output: [1,2] Explanation: Totals5 and7 both become6. Exchanging4 and5 would also work. ``` **Example 2:** ```text Input: aliceSizes = [4], bobSizes = [2,6] Output: [4,6] Explanation: The exchange changes totals4 and8 to6 and6. ``` ### Constraints - `1 <= aliceSizes.length,bobSizes.length <= 10^4`. - `1 <= aliceSizes[i],bobSizes[j] <= 10^5`. - The original candy totals differ. - At least one valid exchange exists. ### Contract considerations The original totals are different, and at least one answer is guaranteed. Either valid pair in the first example is acceptable. ```hint Read the boundary condition Write the two totals after a hypothetical exchange, then solve for the required partner size. ``` ### What a Strong Answer Covers The original totals are different, and at least one answer is guaranteed. Either valid pair in the first example is acceptable. ### Follow-up Questions Optional practice extension, separate from the original task: How could you report every distinct valid size pair instead of one?