Data structures/arrays/triplet sum

data_structures/arrays/find_triplets_with_0_sum.py

@@ -22,3 +22,66 @@ def find_triplets_with_0_sum(nums: list[int]) -> list[list[int]]:
  list(x)
  for x in sorted({abc for abc in combinations(sorted(nums), 3) if not sum(abc)})
  ]
+
+
+def find_triplets_with_0_sum_hashing(arr: list[int]) -> list[list[int]]:
+ """
+ Function for finding the triplets with a given sum in the array using hashing.
+
+ Given a list of integers, return elements a, b, c such that a + b + c = 0.
+
+ Args:
+ nums: list of integers
+ Returns:
+ list of lists of integers where sum(each_list) == 0
+ Examples:
+ >>> find_triplets_with_0_sum_hashing([-1, 0, 1, 2, -1, -4])
+ [[-1, 0, 1], [-1, -1, 2]]
+ >>> find_triplets_with_0_sum_hashing([])
+ []
+ >>> find_triplets_with_0_sum_hashing([0, 0, 0])
+ [[0, 0, 0]]
+ >>> find_triplets_with_0_sum_hashing([1, 2, 3, 0, -1, -2, -3])
+ [[-1, 0, 1], [-3, 1, 2], [-2, 0, 2], [-2, -1, 3], [-3, 0, 3]]
+
+ Time complexity: O(N^2)
+ Auxiliary Space: O(N)
+
+ """
+ target_sum = 0
+
+ # Initialize the final output array with blank.
+ output_arr = []
+
+ # Set the initial element as arr[i].
+ for index, item in enumerate(arr[:-2]):
+ # to store second elements that can complement the final sum.
+ set_initialize = set()
+
+ # current sum needed for reaching the target sum
+ current_sum = target_sum - item
+
+ # Traverse the subarray arr[i+1:].
+ for other_item in arr[index + 1 :]:
+ # required value for the second element
+ required_value = current_sum - other_item
+
+ # Verify if the desired value exists in the set.
+ if required_value in set_initialize:
+ # finding triplet elements combination.
+ combination_array = sorted([item, other_item, required_value])
+ if combination_array not in output_arr:
+ output_arr.append(combination_array)
+
+ # Include the current element in the set
+ # for subsequent complement verification.
+ set_initialize.add(other_item)
+
+ # Return all the triplet combinations.
+ return output_arr
+
+
+if __name__ == "__main__":
+ from doctest import testmod
+
+ testmod()