[LeetCode] 16. 3Sum Closest

最新推荐文章于 2025-09-10 15:24:29 发布

转载最新推荐文章于 2025-09-10 15:24:29 发布 · 58 阅读

0 ·

CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/ZhaoxiCheung/p/LeetCode-3SumClosest.html

文章标签：

#数据结构与算法

本文介绍了一种寻找数组中三个整数之和最接近给定目标值的算法。通过先对数组进行排序，然后使用双指针技术来找到最接近目标值的三数之和。该算法的时间复杂度为O(n^2)。

传送门

Description

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

For example, given array S = {-1 2 1 -4}, and target = 1.

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

思路

题意：给出一串整数值序列，求取最接近目标值的三个数的和

题解：按照3Sum的思路然后更新与目标值最接近的三个数的和

class Solution {
    //22ms
    public int threeSumClosest(int[] nums, int target) {
        Arrays.sort(nums);
        int res = 0,min = Integer.MAX_VALUE;
        int len = nums.length;
        for (int i = 0;i < len - 2;i++){
            int goal = target - nums[i];
            int left = i + 1,right = len - 1;
            while (left < right){
                int sum = nums[i] + nums[left] + nums[right];
                if (sum == target){
                    return sum;
                }
                if (Math.abs(target - sum) < min){
                    res = sum;
                    min = Math.abs(target - sum);
                }
                if (nums[left] + nums[right] < goal){
                    left++;
                }else if (nums[left] + nums[right] > goal){
                    right--;
                }
            }
        }
        return res;
    }
}

转载于:https://www.cnblogs.com/ZhaoxiCheung/p/LeetCode-3SumClosest.html