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16. 3sum Closest

Array Two Pointers Sorting

Problem - 3sum Closest

Medium

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
Explanation: The sum that is closest to the target is 0. (0 + 0 + 0 = 0).

 

Constraints:

  • 3 <= nums.length <= 500
  • -1000 <= nums[i] <= 1000
  • -104 <= target <= 104

Solutions

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class Solution:
    def threeSumClosest(self, nums: List[int], target: int) -> int:
        nums.sort()
        closest = float('inf')

        for i in range(len(nums) - 2):
            # skip dup nums
            if i > 0 and nums[i] == nums[i - 1]:
                continue

            left = i + 1
            right = len(nums) - 1
            while right > left:
                current = nums[i] + nums[left] + nums[right]

                if abs(current - target) < abs(target - closest):
                    closest = current

                elif current < target:
                    left += 1
                elif current > target:
                    right -= 1
                else:
                    return current
        return closest

Submission Stats:

  • Runtime: 351 ms (56.04%)
  • Memory: 18 MB (31.13%)