Description

Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

Example:

Given array nums = [-1, 2, 1, -4], and target = 1.

The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

Submission

This approach firstly fixes one of the 3 numbers and then applies the 2-pointer approach.

class Solution:
    def threeSumClosest(self, nums: List[int], target: int) -> int:
        res = 0
        diff = 9999999999
        comb = []
        
        nums.sort()
        
        length = len(nums)

        for i in range(length-2):
            if i > 0 and nums[i - 1] == nums[i]:
                continue
            
            l = i + 1
            r = length - 1
            
            while l < r:
                s = nums[i] + nums[l] + nums[r]
                new_diff = s - target
                if abs(new_diff) < abs(diff):
                    diff = new_diff
                    res = s
                if new_diff > 0:
                    r -= 1
                else:
                    l += 1
                    
        return res