3Sum Closest

最新推荐文章于 2020-09-08 11:56:16 发布

最新推荐文章于 2020-09-08 11:56:16 发布 · 60 阅读

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本博客介绍了一个算法问题，即在给定数组中找到三个整数，使得它们的和尽可能接近给定的目标值。通过使用排序和双指针技巧，实现了一个高效的解决方案。

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).

public class Solution {
    public int threeSumClosest(int[] nums, int target) {
        Arrays.sort(nums);
        int closest = Integer.MAX_VALUE;
        int sumWhenClosest = 0;
        for (int i = 0; i < nums.length-2; i++) {
        	int start = i+1;
        	int end = nums.length-1;
        	while (start < end) {
        		int sum = nums[i]+nums[start]+nums[end];
        		int newClosest = Math.abs(sum-target);
        		if (newClosest < closest) {
        			closest = newClosest;
        			sumWhenClosest = sum;
        		}
        		if (sum == target) {
        			return target;
        		} else if (sum < target) {
        			start++;
        		} else {
        			end--;
        		}
        	}
        }
        return sumWhenClosest;
    }
}