16. 3Sum Closest

class Solution {
public:
    int threeSumClosest(vector<int>& nums, int target) {
        int res,sum2,cursum2,curdiff,left,right;
        int mindiff=INT_MAX;
        int sz=nums.size();
        sort(nums.begin(),nums.end());
        for(int i=0;i<sz-2;i++){
            if(i>0&&nums[i]==nums[i-1])
                continue;
            sum2=target-nums[i];
            left=i+1;
            right=sz-1;
            while(left<right){
                cursum2=nums[left]+nums[right];
                if(cursum2==sum2)
                    return target;
                curdiff=abs(sum2-cursum2);
                if(curdiff<mindiff){
                    res=nums[i]+cursum2;
                    mindiff=curdiff;
                }
                if(cursum2<sum2){
                    ++left;
                    while(left<right&&nums[left]==nums[left-1])
                        ++left;
                }   
                else{
                    --right;
                    while(left<right&&nums[right]==nums[right+1])
                        --right;
                }
            }
        }
        return res;
    }
};

找和目标值最接近的三个数字和，类似三和问题，只是可以不用管数字重叠，并且要多设置一个统计最小差值的变量