/**
Given an array of integers nums and an integer k, return the total number of 
subarrays whose sum equals to k. 
 A 
                            
                        
                        
                            
                                2022-10-31
                            
                            
                        
                     
                            
                             
                            
                             
                            
                             
                            
                             
                            
                             
                            
                             
                            
                             
                            
                             
                            
                            