Define a multiple stack. write algorithm for its implementation?

Answer 1

A multiple stack program is a program with more than one stack. We are talking about program defined stacks, not the implicit stack that runs behind the scenes. One algorithm would be to create a linked list. The push operation, given the address of the pointer to the head of the stack, would allocate and insert an element in front of the head. Pop would retrieve the head and deallocate it. An incomplete example, using integers as the elements... (For readability, ... indicates tabs.) typedef struct stack_element_s {

... struct stack_element_s *next;

... int element;

} stack_element; int push (stack_element **stack_head, int *value) {

... stack_element *temp;

... stack_element *new_element;

... new_element = malloc (sizeof (stack_element));

... if (new_element == null) return 0; /* allocation failure !!! -- FATAL */

... temp = *stack_head;

... new_element->next = temp;

... new_element->element = *value;

... **stack_head = new_element;

... return 1;

} int pop (stack_element **stack_head, int *value) {

... stack_element *temp;

... temp = *stack_head;

... if (temp == null) return 0; /* stack empty */

... *value = temp->element;

... **stack_head = temp->next;

... free temp;

... return 1;

} stack_element *stack1 = null;

stack_element *stack2 = null; /* showing stack1, stack2 is similar. you can have as many stacks as you want */

int value;

if (!push (&stack1, &value)) exception_handler(); /* exception handler */

if (!pop (&stack1, &value)) stack_empty(); /* stack empty */