1877. Minimize Maximum Pair Sum in Array

1877. Minimize Maximum Pair Sum in Array (Medium)

The pair sum of a pair (a,b) is equal to a + b. The maximum pair sum is the largest pair sum in a list of pairs.

• For example, if we have pairs (1,5), (2,3), and (4,4), the maximum pair sum would be max(1+5, 2+3, 4+4) = max(6, 5, 8) = 8.

Given an array nums of even length n, pair up the elements of nums into n / 2 pairs such that:

• Each element of nums is in exactly one pair, and
• The maximum pair sum is minimized.

Return the minimized maximum pair sum after optimally pairing up the elements.

 

Example 1:

Input: nums = [3,5,2,3]
Output: 7
Explanation: The elements can be paired up into pairs (3,3) and (5,2).
The maximum pair sum is max(3+3, 5+2) = max(6, 7) = 7.

Example 2:

Input: nums = [3,5,4,2,4,6]
Output: 8
Explanation: The elements can be paired up into pairs (3,5), (4,4), and (6,2).
The maximum pair sum is max(3+5, 4+4, 6+2) = max(8, 8, 8) = 8.

 

Constraints:

• n == nums.length
• 2 <= n <= 105
• n is even.
• 1 <= nums[i] <= 105

Companies:
eBay

Related Topics:
Greedy, Sort

Solution 1.

// OJ: https://leetcode.com/problems/minimize-maximum-pair-sum-in-array/
// Author: github.com/lzl124631x
// Time: O(NlogN)
// Space: O(1)
class Solution {
public:
    int minPairSum(vector<int>& A) {
        sort(begin(A), end(A));
        int ans = 0;
        for (int i = 0; i < A.size() / 2; ++i) {
            ans = max(ans, A[i] + A[A.size() - 1 - i]);
        }
        return ans;
    }
};