1877. Minimize Maximum Pair Sum in Array#

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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<sup>5</sup>

  • n is even.

  • 1 <= nums[i] <= 10<sup>5</sup>


Initial Approach

First sort -> then use Two pointer Technique

Solution

class Solution:
    def minPairSum(self, nums: List[int]) -> int:
        nums.sort()
        left=0
        right=len(nums)-1
        maxvalue=0
        while left<right:
            curval=nums[left]+nums[right]
            maxvalue=max(curval,maxvalue)

            left+=1
            right-=1
        return maxvalue

Time Complexity O(N log N)

Space Complexity O(1)

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