Zero-Sum Sub-Arrays
October 13, 2017
This interesting little question comes from Career Cup:
Given an array that contains only the elements -1 and 1, find the number of sub-arrays with a sum of zero. For instance, given the array [-1, 1, -1, 1], there are four sub-arrays that sum to zero: [-1, 1], [1, -1], [-1, 1] and [-1, 1, -1, 1].
Your task is to count the sub-arrays of a -1/1 array that sum to zero. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.
Programming Praxis 