題目連結
給定一個包括 n 個整數的陣列 nums 和 一個目標值 target。找出 nums 中的三個整數，使得它們的和與 target 最接近。返回這三個數的和。假定每組輸入只存在唯一答案。

思路

遍歷三個數字，一個數字順序遍歷，另外兩個採用二分法遍歷

程式碼

class Solution:
    def threeSumClosest(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
 

        if len(nums) < 3:
            raise Exception('input error')
        nums.sort()
        threeNums = nums[0] + nums[1] + nums[2]
        differ = abs(threeNums - target)
        ans = threeNums
        for i in range(len(nums) - 2):
            low = i + 1
            high = len(nums) - 1
 

            while(low < high):
                threeNums = nums[i] + nums[low] + nums[high]
                if abs(threeNums - target) < differ:
                    differ = abs(threeNums - target)
                    ans = threeNums
                if threeNums == target:
                    return
 
 target
                elif threeNums < target:
                    while low < high and nums[low + 1] == nums[low]:
                        low += 1
                    low += 1
                else:
                    while low < high and nums[high - 1] == nums[high]:
                        high -= 1
                    high -= 1
        return ans