Find if there is a subarray with 0 sum | GeeksforGeeks

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[StingSting]

The reason why this works is that if there is a repeating prefix sum, that means adding all the elements before that has resulted in zero. Here, prefix sums are 1, 5, 3, 1 meaning that whatever was elements were added to form 1 add up to 0 themselves. Meaning, 4, -2, -2 become 0!

[hardikraj]

Explanation:
Suppose we have the prefix sums as : 1, 5, 3, 1, 6, 2, 5
Now see as we move from prefix sum 1->5 we have an increment of 4. This means our sub-array has [4] or [1, 2, 1] or [2, 2], basically elements that add upto 4. Now as we go from 5->1, we again have a drop of 4, so our sub-array can have elements as [-4], [-5, 1] or [10, -16, 2], basically which makes our sum as -4. Now as we are considering a contiguous sub-array, the elements causing increment by 4 and decrement by 4 will come in the same sub-array making the sum as 0

[anujsaini]

weak explanation you just read whatever was written on the back slide or whatever document. this is just like text to speech program. you should explain it well

[MrAbhay]

Explanation: If at any point in the iteration, the prefix sum repeats, that means the subarray starting from previous prefix sum and current prefix sum, has a sum of zero. That is why there is no increase in the sum.

[srs.shashank]

Hi, if for eg array A=[4, -2, 1, -2, 1, 3] in this case the prefix sums would be=4, 2, 3, 1, 2, 5 . So here prefix sum= 2 repeats whereas there is no contiguous sub-array with sum =0. Here the OR condition might fail. Kindly correct me if I am wrong.

[thestone]

How can we calculate the first index of subaaray when sumSet.find() statement is trus? Please help

[gauravkvtamboli]

This code(Hashing based one) didnt work for int arr[] = {1, 4, 2, 2, -5}; here {1, 4, -5} is the subarray for which sum=0, is this solution only applicable for continuous subarray finding only

[martialcoder]

Can it be done by O(N) which will reduce the time of the program?

[shriyanshagarwal]

I came to know from this problem that hashset is faster than arraylist

[spicytuna]

its great the code is short. but you forgot to explain why this works.

[jiba_jyoti_panda_]

Can anyone provide an implementation of this solution in python language?

[sagarsakre]

Shoudn't the title be renamed to "Find if there's a contiguous subarray with 0 sum" ?

[atefnazi]

these videos are crap. He is just going through the description given in the geeksforgeeks website. He is ranting about how this solution derived

[ankitapawaskar]

hey in second eg -3 and 3 form up a zero