leetcode_016 3Sum Closest(TwoPointers)

Posted 2020-09-18

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).

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同leetcode015

Python实现

class Solution(object):
    def threeSumClosest(self, nums, target):
        nums.sort()
        ans = nums[0] + nums[1] + nums[2]
        tsum = 0
        length = len(nums)
        for i in range(length):
            left = i + 1
            right = length - 1
            while left < right:
                tsum = nums[i] + nums[left] + nums[right]
                if abs(tsum - target) < abs(ans -target):
                    ans = tsum
                if tsum <= target:
                    left += 1
                else:
                    right -= 1
        return ans