[Solved] Given an integer array nums of length n 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.

Question

Given an integer array nums of length n 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 1:

Input: nums = [-1,2,1,-4], target = 1
Output: 2
Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

Example 2:

Input: nums = [0,0,0], target = 1
Output: 0

Constraints:

• 3 <= nums.length <= 1000
• -1000 <= nums[i] <= 1000
• -104 <= target <= 104

Python Solution

class Solution:
    def threeSumClosest(self, nums: List[int], target: int) -> int:
        closest = nums[0]+nums[1]+nums[2]
        nums.sort()
        for i in range(len(nums)-2):
            l = i+1
            r = len(nums)-1
            while l<r:
                total = nums[i] + nums[l] + nums[r]
                if abs(total-target) < abs(target-closest):
                    closest = total
                if total>target:
                    r-=1
                elif total<target:
                    l+=1
                else:
                    return closest
        return closest