[LeetCode]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).

思考：类似3Sum。

class Solution {

public:

    int threeSumClosest(vector<int> &num, int target) {

        // IMPORTANT: Please reset any member data you declared, as

        // the same Solution instance will be reused for each test case.

        int ret=INT_MAX;

		sort(num.begin(),num.end());

		int i,j,k,sum;

		int min=INT_MAX;

		for(i=0;i!=num.size();i++)

		{

			j=i+1;

			k=num.size()-1;

			while(j<k)

			{

				sum=num[i]+num[j]+num[k];

				if(abs(target-sum)<min)

				{

					ret=sum;

					min=abs(target-sum);

				}

				if(sum==target) return target;

				else if(sum<target) j++;

				else k--;

			}

		}

		return ret;

    }

};