find_Triplets_with_zero_sum.py

"""
  Author : Mohit Kumar
  
  Python program to find triplets in a given  array whose sum is zero 
"""

# function to print triplets with 0 sum
def find_Triplets_with_zero_sum(arr, num):

    """find triplets in a given  array whose sum is zero

    Parameteres :
        arr : input array
        num = size of input array
    Output :
        if triplets found return their values
        else return "No Triplet Found"
    """
    # bool variable to check if triplet found or not
    found = False

    # sort array elements
    arr.sort()

    # Run a loop until l is less than r, if the sum of array[l], array[r] is equal to zero then print the triplet and break the loop
    for index in range(0, num - 1):

        # initialize left and right
        left = index + 1
        right = num - 1

        curr = arr[index]  # current element

        while left < right:

            temp = curr + arr[left] + arr[right]

            if temp == 0:
                # print elements if it's sum is zero
                print(curr, arr[left], arr[right])

                left += 1
                right -= 1

                found = True

            # If sum of three elements is less  than zero then increment in left
            elif temp < 0:
                left += 1

            # if sum is greater than zero than decrement in right side
            else:
                right -= 1

    if found == False:
        print(" No Triplet Found")


# DRIVER CODE STARTS

if __name__ == "__main__":

    n = int(input("Enter size of array\n"))
    print("Enter elements of array\n")

    arr = list(map(int, input().split()))

    print("Triplets with 0 sum are as : ")

    find_Triplets_with_zero_sum(arr, n)

"""
SAMPLE INPUT 1 :
	Enter size of array : 5 
	Enter elements of array : 0, -1, 2, -3, 1
OUTPUT :
	Triplets with 0 sum are as : 
				    -3 1 2
				    -1 0 1
COMPLEXITY ANALYSIS :
Time Complexity : O(n^2).
    Only two nested loops is required, so the time complexity is O(n^2).
Auxiliary Space : O(1), no extra space is required, so the time complexity is constant.
"""