【leetcode】16. 3Sum Closest

/**
* 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).
*/
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

int threeSumClosest(vector<int>& nums, int target)
{

int len = nums.size();

int closest = INT_MAX;
int l = 0, r = 0;
int sum = 0;
for (int i = 0; i < len; i++)
{
l = i + 1;
r = len - 1;
while (l < r)
{
sum = nums[i] + nums[l] + nums[r];
if (closest == INT_MAX)
closest = sum;
else
closest = abs(sum - target) < abs(closest - target) ? sum : closest;

if (sum == target)
{
return target;
}
else if (sum < target)
l++;
else
r--;
}
}

return closest;
}

int main()
{
vector<int> nums = { -1, 2, 1, -4 };
sort(nums.begin(), nums.end());
//-4 -1 1 2
cout << threeSumClosest(nums, 1);
system("pause");
return 0;
}

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