【leetcode】3Sum Closet

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).

 

class Solution {
public:
    int threeSumClosest(vector<int>& nums, int target) {
        sort(nums.begin(),nums.end());

        int ret;
        bool first=true;

        for(int i=0;i<nums.size();i++)
        {
            int j=i+1;
            int k=nums.size()-1;

            while(j<k)
            {
                int sum=nums[i]+nums[j]+nums[k];

                if(first)
                {
                    ret=sum;
                    first=false;
                }else
                {
                    if(abs(sum-target)<abs(ret-target))
                        ret=sum;
                }

                if(ret==target)
                    return ret;

                if(sum>target)
                    k--;
                else
                    j++;
            }
        }

        return ret;
    }
};