Count number of ways to split the array at index i such that subarray sums are equal
int number_of_subarray_at_i_split = 0 ; if ( prefix_element_count . ContainsKey ( difference ) ) number_of_subarray_at_i_split = prefix_element_count [ difference ] ; if ( suffix_element_count . ContainsKey ( - difference ) ) number_of_subarray_at_i_split += suffix_element_count [ - difference ] ;