Leetcode | | 3Sum Closest problem

Problem:

Given an array S of n integers, find three integers in S such, the sum was closest to a Given number, target. Return the sum of the three integers. You may assume this each input would has exactly one solution.    For example, given array S = {-1 2 1-4}, and target = 1.    The sum is closest to the target is 2. (-1 + 2 + 1 = 2).

Given an array, the number of three numbers is closest to the target, and the result is nearly the default unique

Thinking:

(1) is not very familiar, this problem is only to seek three number and for a specific value of the deformation

(2) still use greedy thought , three-pointer binary search, look for three number and the absolute value of the difference with the minimum sum of the values, the flag is used in the positive and negative relationship .

Code:

Class Solution {Public:int threesumclosest (vector<int> &num, int target) {int index;    BOOL Flag=true;        Sort (Num.begin (), Num.end ());        if (num.at (0) +num.at (1) +num.at (2) >target) index=num.at (0) +num.at (1) +num.at (2)-target;                else {index=target-(num.at (0) +num.at (1) +num.at (2));            Flag=false;            } for (int i = 0; i < num.size (); ++i) {int p = i + 1, q = num.size ()-1;            int sum=0;                while (P < q) {sum = Num[i] + num[p] + num[q];                if (sum = = target) {return sum;                    }//if else if (sum < target)//And too small, p moves backwards {++p;                        if (target-sum<index) {index=target-sum;                    Flag=false;       }} else     And too large, Q moves forward {--q;                        if (sum-target<index) {index=sum-target;                    Flag=true;        }}//else}//while}//for if (flag) return index+target;    else return target-index; }};<strong></strong>

Leetcode | | 3Sum Closest problem