Check if subarray with 0 sum is exists or not

Given an array of integers, check if array contains a sub-array having 0 sum.

 

For example,


Input:  { 3, 4, -7, 3, 1, 3, 1, -4, -2, -2 }

Output: Subarray with 0 sum exists

 
The sub-arrays with 0 sum are:

{ 3, 4, -7 }
{ 4, -7, 3 }
{ -7, 3, 1, 3 }
{ 3, 1, -4 }
{ 3, 1, 3, 1, -4, -2, -2 }
{ 3, 4, -7, 3, 1, 3, 1, -4, -2, -2 }

 


 

We can easily solve this problem in linear time by using hashing. We can use set to check if sub-array with zero sum is present in the given array or not. We traverse the given array, and maintain sum of elements seen so far. If sum is seen before (i.e. sum exists in set), we return true as there exists at-least one sub-array with zero sum which ends at current index else we insert the sum into the set.

C++

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Output:


Subarray exists

Java

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Output:


Subarray exists


 

The time complexity of proposed solution is O(n) and auxiliary space used by the program is O(n).

 
Also See: Print all sub-arrays with 0 sum

 
Exercise: Extend the solution for non-zero sum of sub-array.

 
Thanks for reading.




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H. Guijt
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H. Guijt

Instead of arguments (int A[], int n), we can also use (std::initializer_list A). The function call would then be zeroSumSubArray ({4, 2, -3, -1, 0 4});, and the for-loop could use range-based for.

Roshan
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Roshan

int A[] = { 2, 1, -4, -1, 4 };
fails

Roshan
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Roshan

by mistake, ign0re

Cke
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This won’t work on say [3, -50, 1, -4]

Am I right?

Cke
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Yes I’m. Tested it ou your code!

Cke
Guest

Ok, I see it now, you are working only on continious sub-arrays 😉

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