## Problem

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).

## Solution

class Solution { public: int threeSumClosest(vector<int>& nums, int target) { int minDiff = INT_MAX; if(nums.size()<3) return minDiff; sort(nums.begin(), nums.end()); for(int i=0; i<nums.size()-2; i++){ int left = i+1; int right = nums.size()-1; while(left < right){ int currDiff = nums[i] + nums[left] + nums[right] - target; //update diff if(abs(minDiff) > abs(currDiff)) minDiff = currDiff; //special case if(currDiff == 0) break; else if (currDiff < 0) left++; else right--; } } return target + minDiff; } };

## Analysis

This problem is similar to 3Sum problemĀ http://mytechroad.com/leetcode-c-3sum/

Time complexity: O(n^2)