力扣——3sum closest（最接近的三数之和）python 实现

题目描述：

中文：

给定一个包括 n 个整数的数组 nums 和 一个目标值 target。找出 nums 中的三个整数，使得它们的和与 target 最接近。返回这三个数的和。假定每组输入只存在唯一答案。

英文：

Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

class Solution(object):
    def threeSumClosest(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        mindiff = 10000
        nums.sort()
        res = 0
        for i in range(len(nums)):
            left = i+1
            right = len(nums)-1
            while left < right:
                sum = nums[left] + nums[right] + nums[i]
                diff = abs(target - sum)
                if diff < mindiff:
                    mindiff = diff
                    res = sum
                if target == sum:
                    return sum
                elif sum < target:
                    left += 1
                else:
                    right -= 1                      

        return res

题目来源：力扣题库