Python Program to Find if there is any subarray with sum equal to 0

October 14, 2022

Subarray with sum equal to 0 in Python

Here, in this page we will discuss the program to find if there is any Subarray with sum equal to 0 in Python programming language. If such subarray is present then print True otherwise print False.

Example :

  • Input :  [ 4, 2, -3, 1, 6 ]
  • Output :  True
  • Explanation :  There is a subarray with zero sum from index 1 to 3, { 2+(-3)+1 = 0 }
Subarray with sum equal to 0 in Python

Method Discussed :

  • Method 1 : Naïve Approach
  • Method 2 : Using Hashing

Method 1 :

  • Run a outer loop for index 0 to l-1.
  • Run a nested loop from index i+1 to l,
  • Find sum, if it is equal to 0, then print True.
  • Otherwise, print False.

Time and Space Complexity

  • Time Complexity : O(n2)
  • Space Complexity : O(1)

Method 1 : Code in Python

Run 
def subArray(arr, l):
    for i in range(l - 1):
        s = arr[i]
        for j in range(i + 1, l):
            s += arr[j]
            if s == 0:
                return True
    return False


array = [4, 2, -3, 1, 6]

print(subArray(array, len(array)))

Output

True

Method 2 :

  • Initialize a set s and add 0 to s
  • Initialize a variable total = 0
  • Iterate arr using for loop
  • For each iteration add the value to total
  • If total in s(set) return True
  • Add value of total to s
  • At end of for loop return False

Time and Space Complexity

  • Time Complexity : O(n)
  • Space Complexity : O(n+1)

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Method 2 : Code in Python

Run 
def subArray(arr):
    s = set()
    s.add(0)

    total = 0

    for i in arr:
        total += i

        if total in s:
            return True

        s.add(total)
    return False


array = [-3, 2, 3, 1, 6]

print(subArray(array))

Output

False

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