1877. Minimize Maximum Pair Sum in Array

Problem

Tags: Array, Two Pointers, Greedy, Sorting

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 <= 10^5
• n is even.
• 1 <= nums[i] <= 10^5

Code

JS

// 1877. Minimize Maximum Pair Sum in Array (8/17/53378)
// Runtime: 656 ms (1.72%) Memory: 56.99 MB (49.42%) 

/**
 * @param {number[]} nums
 * @return {number}
 */
var minPairSum = function(nums) {
    nums.sort((a, b) => a - b);
    let max = 0;
    for(var i = 0; i < nums.length / 2; i++) {
        let sum = nums[i] + nums[nums.length - 1 - i];
        max = sum > max ? sum : max;
    }
    return max;
};