Question

Number of ways to divide an array into three subarrays of equal sum

Answer 1

Given a array of n numbers. Our task is to find out the number of ways to divide the array into three contiguous parts such that the sum of three parts is equal. In other words, we need to find the number of index pairs i and j such that sum of elements from 0 to i-1 is equal to sum of elements from i to j is equal to the sum of elements from j+1 to n-1.