【LeetCode】0016 最接近的三数之和

https://leetcode-cn.com/problems/3sum-closest/

# -*- coding:utf-8 -*-

class Solution(object):
    def threeSumClosest(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        dis = float('inf')
        res = []
        nums.sort()
        for i in range(len(nums) - 2):
            left = i + 1
            right = len(nums) - 1
            while left < right:
                if abs(nums[i] + nums[left] + nums[right] - target) < dis:
                    dis = abs(nums[i] + nums[left] + nums[right] - target)
                    res = [nums[i], nums[left], nums[right]]
                    # 判断指针移动方向
                if nums[i] + nums[left] + nums[right] - target < 0:
                    left += 1
                elif nums[i] + nums[left] + nums[right] - target > 0:
                    right -= 1
                else:
                    return target
        return sum(res)
if __name__ == '__main__':
    nums = [-1, 2, 1, -4]
    nums = [1, 2, 4, 8, 16, 32, 64, 128]
    target = 82
    print(Solution().threeSumClosest(nums, target))

思路：这道题和上面的那个三数之和十分相似，一样是使用指针搜索，只不过不再以和为0作为判断，对应的引入一个变量dis用来表示当前集合和target的距离，同时根据当前集合的和 和 target的大小关系决定指针的移动。