LeetCode 3Sum Closest

链接：https://oj.leetcode.com/problems/3sum-closest/

跟3-sum的思路是一样的。根据sum与target的大小关系，分别移动数组两端的“指针”，同时记录sum与target最小的距离

class Solution {
public:
    int threeSumClosest(vector<int> &num,int target)
		{
			sort(num.begin(),num.end());
			int sum;
			int d=-1;
			int l=1,r=num.size()-1;
			for(int i=0;i<num.size()-2;i++)
			{
				l=i+1;
				r=num.size()-1;

				while(l<r)
				{
			    	int t=num[i]+num[l]+num[r];
					int c=C(t,target);
					if(t>target)
						r--;
					else
						l++;
					if(c<d||d==-1)
					{
						sum=t;
						d=c;
					}
				}
			}
			return sum;

		}
		int C(int t,int target)
		{
			return target>t?target-t:t-target;
		}
};