leetcode 16. 3Sum Closest

import java.util.Arrays;

//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 static void main(String[] args) {
		int[] a = {1,1,1,1};
		int result = threeSumClosest(a,-100);
		System.out.println(result);
	}
	
	public static int threeSumClosest(int[] nums, int target) {
        int result = 0;
        int cha = 1000;
        Arrays.sort(nums);															//先对数组排序
        for(int i = 0;i<nums.length-2;i++){											//与上一题差不多，遍历数组，从当前元素之后的元素段首尾相加：1（当前），1（首），1，1（尾）
        	int j = i+1;
        	int end = nums.length-1;
        	while(j<end){															//首小于尾时循环
        		if(nums[i]+nums[j]+nums[end] == target){
        			return target;
        		}else if(nums[i]+nums[j]+nums[end]<target){							//根据三数相加与target的差值调整首尾的位置
        			if(cha>Math.abs(target-nums[i]-nums[j]-nums[end])){
        				cha = Math.abs(target-nums[i]-nums[j]-nums[end]);
        				result = nums[i]+nums[j]+nums[end];
        			}
        			j++;
        		}else{
        			if(cha>Math.abs(target-nums[i]-nums[j]-nums[end])){
        				cha = Math.abs(target-nums[i]-nums[j]-nums[end]);
        				result = nums[i]+nums[j]+nums[end];
        			}
        			end--;
        		}
        	}
        }
        return result;
    }
	
}