leetcode刷题笔记(Golang)--16. 3Sum Closest

原题链接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).

解题思路：与3sum问题基本一致

func threeSumClosest(nums []int, target int) int {
    var res int = nums[0] + nums[1] + nums[2]
    sort.Ints(nums)
    lg := len(nums)
    for i := 0; i < lg-2; i++ {
        l := i + 1
        r := lg - 1
        for l < r {
            _sum := nums[i] + nums[l] + nums[r]
            if _sum == target {
                return target
            } else if _sum > target {
                r--
            } else {
                l++
            }
            if math.Abs(float64(_sum-target)) < math.Abs(float64(res-target)) {
                res = _sum
            }
        }
    }
    return res
}