3 Sum Closest

题目：

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.

分析：

双指针，不断更新最小diff.不知道为什么不去重。

解法：

    public int threeSumClosest(int[] nums, int target) {
        int sum = 0, minDiff = Integer.MAX_VALUE;
        Arrays.sort(nums);
        for(int j = 0; j < nums.length - 2; j++){

                int first = nums[j], start = j + 1, end = nums.length - 1;            
                while(start < end){
                    int second = nums[start], third = nums[end];
                    int localSum = first + second + third;
                    int diff = Math.abs(target - localSum);
                    if(diff < minDiff){
                        sum = localSum;
                        minDiff = diff;
                    }
                    if(localSum < target){
                        start ++;                       
                    }else{
                        end --;
                    }                               
                }

        }
        return sum;        
    }