561. Array Partition I
package LeetCode_561 /** * 561. Array Partition I * https://leetcode.com/problems/array-partition-i/ * Given an integer array nums of 2n integers, group these integers into n pairs (a1, b1), (a2, b2), ..., * (an, bn) such that the sum of min(ai, bi) for all i is maximized. Return the maximized sum. Example 1: Input: nums = [1,4,3,2] Output: 4 Explanation: All possible pairings (ignoring the ordering of elements) are: 1. (1, 4), (2, 3) -> min(1, 4) + min(2, 3) = 1 + 2 = 3 2. (1, 3), (2, 4) -> min(1, 3) + min(2, 4) = 1 + 2 = 3 3. (1, 2), (3, 4) -> min(1, 2) + min(3, 4) = 1 + 3 = 4 So the maximum possible sum is 4. Example 2: Input: nums = [6,2,6,5,1,2] Output: 9 Explanation: The optimal pairing is (2, 1), (2, 5), (6, 6). min(2, 1) + min(2, 5) + min(6, 6) = 1 + 2 + 6 = 9. * */ class Solution { /* * solution: greedy, sort array, set two number as a group then sum up every group's first num, * Time:O(nlogn), Space:O(1) * */ fun arrayPairSum(nums: IntArray): Int { nums.sort() var result = 0 for (i in nums.indices step 2) { result += nums[i] } return result } }