[leetcode]16. 3Sum Closest

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).

先看别人的解法写的15题，再写16题觉得还是比较easy的

最开始没有加if(sum==target)  return target，对有些测试集显示超时，其实只要找到了sum==target就不需要再继续判断了

class Solution {
public:
    int threeSumClosest(vector<int>& nums, int target) {
        int length = nums.size();
   //     sort(nums.begin(),nums.end());
        int closest = 2147483647;
        for(int i=0; i<length; i++)
        {
            for(int j=i+1; j<length; j++)
            {
                for(int k=j+1; k<length; k++)
                {
                    int sum = nums[i] + nums[j] + nums[k];
                    if(sum==target)
                        return target;
                    if(abs(sum-target)<abs(closest))
                        closest = sum- target;
                }
            }
        }
        return (target+closest);
    }
};