数据结构算法操作试题(C++/Python)——最接近的三数之和

class Solution:
    def threeSumClosest(self, nums: List[int], target: int) -> int:
        nums.sort()
        if sum(nums[-3:]) <= target:
            return sum(nums[-3:])
        if sum(nums[:3]) >= target:
            return sum(nums[:3])
        pre_flag = "flag"
        flag = pre_sum_val = sum_val = first_flag = 0
        for i in range(len(nums) - 2):
            start = i + 1
            end = len(nums) - 1
            while start < end:
                sum_val = nums[start] + nums[end] + nums[i]
                if sum_val > target:
                    end -= 1
                    flag = 0
                elif sum_val < target:
                    start += 1
                    flag = 1
                else:
                    return target
                if pre_flag != flag and pre_flag != "flag":
                    if not first_flag:
                        minDis = self.judgeAbs(sum_val, pre_sum_val, target)
                        first_flag = 1
                    minDis = self.judgeAbs(self.judgeAbs(sum_val, pre_sum_val, target), minDis, target)
                    pre_flag = "flag"
                else:
                    pre_flag = flag
                    pre_sum_val = sum_val
        return minDis
    
    def judgeAbs(self, sum_1, sum_2, target):
        return sum_2 if abs(sum_1 - target) >= abs(sum_2 - target) else sum_1