Java [leetcode 16] 3Sum Closest

题目描述：

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).

解题思路：

这个跟3Sum的思路差不多，不过实现的过程就简单多了。外面一个大的循环，里面也是从两边开始，如果三个数之和减去目标值的绝对值较小，则更新之并记录此三个数之和。

代码如下：

public class Solution {

    public int threeSumClosest(int[] nums, int target) {

		int length = nums.length;

		int min = Integer.MAX_VALUE;

		int left, right, comp, result = 0;



		if (length < 3)

			return 0;

		Arrays.sort(nums);



		for (int i = 0; i < length - 2; i++) {

			left = i + 1;

			right = length - 1;

			while (left < right) {

				comp = nums[i] + nums[left] + nums[right];

				if (Math.abs(comp - target) < min){

					min = Math.abs(comp - target);

					result = comp;

				}

				if (comp > target)

					right--;

				else if (comp < target)

					left++;

				else

					return target;

			}

		}

		return result;

	}

}