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Tested Python solution for LeetCode 16 with 16 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 16 # by problem number
lcpy gen -s three_sum_closest # by problem name
nums of length n and an integer target, find three integers at distinct indices 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.
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).
Input: nums = [0,0,0], target = 1
Output: 0
Explanation: The sum that is closest to the target is 0. (0 + 0 + 0 = 0).
class Solution:
# Time: O(n^2)
# Space: O(1) (ignoring sort space)
def three_sum_closest(self, nums: list[int], target: int) -> int:
nums.sort()
n = len(nums)
closest = nums[0] + nums[1] + nums[2]
for i in range(n - 2):
left = i + 1
right = n - 1
while left < right:
current_sum = nums[i] + nums[left] + nums[right]
# Update closest if this sum is nearer to target
if abs(current_sum - target) < abs(closest - target):
closest = current_sum
if current_sum == target:
return current_sum
elif current_sum < target:
left += 1
else:
right -= 1
return closest
| Time | Space |
|---|---|
| O(n^2) | O(1) (ignoring sort space) |