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) {
if(nums.size()<3) return 0;
int number=nums[0]+nums[1]+nums[2];
std::sort(nums.begin(),nums.end());
for(int i1=0;i1<nums.size();i1++){
if(i1>0 && nums[i1]==nums[i1-1]) continue;
int i2=i1+1;
int i3=nums.size()-1;
while(i2<i3){
int sum=nums[i1]+nums[i2]+nums[i3];
if(sum==target) return sum;
if(abs(target-number)>abs(target-sum)) number=sum;
if(sum>target){
i3--;
}else{
i2++;
}
}
}
return number;
}
};