Python: Find unique triplets whose three elements gives the sum of zero from an array of n integers

Python Basic - 1: Exercise-4 with Solution

Write a Python program to find unique triplets whose three elements gives the sum of zero from an array of n integers.

Pictorial Presentation:

Sample Solution:

Python Code :

def three_sum(nums):
  result = []
  nums.sort()
  for i in range(len(nums)-2):
    if i> 0 and nums[i] == nums[i-1]:
      continue
    l, r = i+1, len(nums)-1
    while l < r:
      s = nums[i] + nums[l] + nums[r]
      if s > 0:
        r -= 1
      elif s < 0:
          l += 1
      else:
        # found three sum
        result.append((nums[i], nums[l], nums[r]))
        # remove duplicates
        while l < r and nums[l] == nums[l+1]:
          l+=1
          while l < r and nums[r] == nums[r-1]:
            r -= 1
            l += 1
            r -= 1
          return result

x = [1, -6, 4, 2, -1, 2, 0, -2, 0 ]
print(three_sum(x))

Sample Output:

[(-6, 2, 4)]

Flowchart:

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