 6/21/2017 - 9:30 AM

## 16. 3Sum Closest

1. 3Sum Closest
``````class Solution(object):
def threeSumClosest(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: int
"""
nums = sorted(nums)
self.closest = float('inf')
firstIndex = 0
while firstIndex <= len(nums) - 3:
self.twoSum(nums, firstIndex, firstIndex+1, target)
firstIndex += 1
while nums[firstIndex] == nums[firstIndex - 1] and firstIndex <= len(nums) - 3:
firstIndex += 1
return self.closest

def twoSum(self, nums, firstIndex, beginIndex, target):
endIndex = len(nums) - 1
while beginIndex < endIndex:
curSum = nums[firstIndex] + nums[beginIndex] + nums[endIndex]
self.closest = curSum if abs(curSum-target) < abs(self.closest-target) else self.closest
if curSum < target:
beginIndex += 1
while nums[beginIndex] == nums[beginIndex - 1] and beginIndex < endIndex:
beginIndex += 1
elif curSum > target:
endIndex -= 1
while nums[endIndex] == nums[endIndex + 1] and beginIndex < endIndex:
endIndex -= 1
else:
break``````

https://leetcode.com/problems/3sum-closest/#/description

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).
``````