16. 3Sum Closest

Posted on | In |
  • Source : Link
  • Author : Han
  • Date : 2022-01-26

Problems

Given an integer array nums of length n and an integer target, find three integers in nums such that the sum is closest to target.

Return the sum of the three integers.

You may assume that each input would have exactly one solution.

Example 1:

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Input: nums = [-1,2,1,-4], target = 1
Output: 2
Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

Example 2:

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Input: nums = [0,0,0], target = 1
Output: 0

Solution

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import kotlin.math.abs

class Solution {
    fun threeSumClosest(nums: IntArray, target: Int): Int {
        nums.sort()

        var closest: Int? = null
        var diff = 0

        for (i in 0 until nums.size - 2) {
            if (i > 0 && nums[i] == nums[i - 1]) {
                continue
            }

            var left = i + 1
            var right = nums.size - 1

            while (left != right) {
                val sum = nums[left] + nums[right] + nums[i]

                when {
                    sum < target -> left++
                    sum > target -> right--
                    else -> return sum
                }

                when (closest) {
                    null -> {
                        closest = sum
                        diff = abs(target - closest)
                    }
                    else -> {
                        val currDiff = abs(target - sum)
                        when {
                            currDiff < diff -> {
                                closest = sum
                                diff = currDiff
                            }
                        }
                    }
                }
            }
        }

        return closest ?: 0
    }
}