# Leetcode: 3Sum Closest

3Sum Closest Similar Problems:

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).
```

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

```## Blog link: https://code.dennyzhang.com/3sum-closest
## Basic Ideas: two sum
## Complexity: Time O(n*n), Space O(1)
class Solution:
def threeSumClosest(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: int
"""
import sys
length = len(nums)
if length <=2: return sum(nums)
nums.sort()
res = sum(nums[0:3])
for i in range(length-2):
l, r = i+1, length-1
while l<r:
v = nums[i]+nums[l]+nums[r]
if v == target: return v
if abs(v-target) < abs(res-target): res = v

if v > target:
# make v smaller
r -= 1
else:
l += 1

return res
```

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