連結：

題目：

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。
例如，給定陣列 nums = [-1，2，1，-4], 和 target = 1.
與 target 最接近的三個數的和為 2. (-1 + 2 + 1 = 2).

class Solution:
    def threeSumClosest(self, nums, target):
        closest = 1000
        closesum = 0
        nums =
 
 sorted(nums)
        for i in range(len(nums)-2):
            if i>0 and nums[i] == nums[i-1]:
                continue
            j = i + 1
            k = len(nums) - 1
            while j<k:
                if j-1 != i and nums[j] == nums[j-1]:
                    j += 1
                    continue
 

                if nums[i]+nums[j]+nums[k]-target == 0:
                    closesum = nums[i]+nums[j]+nums[k]
                    return closesum
                elif nums[i]+nums[j]+nums[k]-target < 0:
                    if abs(nums[i]+nums[j]+nums[k]-target) < closest:
                        closest =
 
 abs(nums[i]+nums[j]+nums[k]-target)
                        closesum = nums[i]+nums[j]+nums[k]
                    j += 1
                elif nums[i]+nums[j]+nums[k]-target > 0:
                    if abs(nums[i]+nums[j]+nums[k]-target) < closest:
                        closest = abs(nums[i]+nums[j]+nums[k]-target)
                        closesum = nums[i]+nums[j]+nums[k]
                    k -= 1
        return closesum

別人的解法1:

class Solution:
    def threeSumClosest(self, nums, target):
        nums = sorted(nums)
        #res表示最小的三數和
        res = sum(nums[:3])
        for i in range(len(nums)-2):
            j = i + 1
            k = len(nums) - 1
            while j<k:
                temp = nums[i] + nums[j] +nums[k]
                #更新res
                if abs(res - target) > abs(temp-target):
                    res = temp
                if target < temp:
                    k-=1
                else:
                    j+=1
        return res

看了別人的解法後，對我的解法做優化：80ms，擊敗83%

class Solution:
    def threeSumClosest(self, nums, target):
        closesum = sum(nums[:3])
        nums = sorted(nums)
        for i in range(len(nums)-2):
            if i>0 and nums[i] == nums[i-1]:
                continue
            j = i + 1
            k = len(nums) - 1
            while j < k:
                if j-1 != i and nums[j] == nums[j-1]:
                    j += 1
                    continue
                temp = nums[i]+nums[j]+nums[k]
                if temp-target == 0:
                    return temp
                #把這個if抽出來了
                if abs(temp-target) < abs(closesum-target):
                    closesum = temp
                if temp-target < 0:
                    j += 1
                elif temp-target > 0:     
                    k -= 1
        return closesum