Explain finding triplets summing to zero.
01
01
Understand the problem
arraystwo-pointers
02
02
Attempt it yourself
Sketch your approach before reading the solution — that's what interviews test.
Stuck? AI Nudge Available
Get a conceptual hint to guide your logic without spoiling the final implementation.
03
03
Study the solution
The solution is waiting
Give it an honest attempt first — then compare your thinking with the full walkthrough.
04
04
Read the code
Sort + two pointers
Run Playgrounddef three_sum(nums):
nums.sort()
res = []
for i in range(len(nums) - 2):
if i > 0 and nums[i] == nums[i - 1]:
continue # skip duplicate fixed value
left, right = i + 1, len(nums) - 1
while left < right:
total = nums[i] + nums[left] + nums[right]
if total < 0:
left += 1
elif total > 0:
right -= 1
else:
res.append([nums[i], nums[left], nums[right]])
left += 1; right -= 1
while left < right and nums[left] == nums[left - 1]:
left += 1
while left < right and nums[right] == nums[right + 1]:
right -= 1
return res
# --- demo ---
print(three_sum([-1, 0, 1, 2, -1, -4])) # [[-1, -1, 2], [-1, 0, 1]]05
05
Join the discussion
Discussion (0)
Sign in to join the discussion.
No responses yet. Be the first to share what you think.