16. 3Sum Closest

[yunshuipiao]

16. 3Sum Closest

Given an array nums of n integers 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:

Given array nums = [-1, 2, 1, -4], and target = 1.

The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

解法

与上一题的方法相同，不过这题判断更为简单，绝对值为0 就返回。

特别注意下标合法性的判断

import org.testng.annotations.Test

fun threeSumClosest(nums: IntArray, target: Int): Int {
    var result = 0
    if (nums.size < 3) {
        return 0
    }
    var tempNums = nums
    tempNums.sort()
    result += tempNums[0] + tempNums[1] + tempNums[2]
    for (index in 0..tempNums.size - 3) {
        var l = index + 1
        var r = tempNums.size - 1
        while (l < r) {
            val tempResult = tempNums[index] + tempNums[l] + tempNums[r]
            if (tempResult > target) {
                r -= 1
            } else if (tempResult < target) {
                l += 1
            } else {
                return tempResult
            }
            if (Math.abs(tempResult - target) <= Math.abs(result - target)) {
                result = tempResult
            }
        }
    }
    return result
}


@Test
fun _0016() {
    arrayListOf(intArrayOf(1, 1, -1, -1, 3)).forEach {
        println(threeSumClosest(it, 1))
    }
}