Answer to Question #239590 in C for Ram

Question

A stack data structure is given with push and pop operations. WAP to implement a queue using instances of stack data structure and operations on them.

Answer 1

#include <stdio.h>
#include <stdlib.h>


struct Stack {
	int top;
	unsigned size;
	int* stackArray;
};
struct Stack* createStack(unsigned size)
{
	struct Stack* stack = (struct Stack*)malloc(sizeof(struct Stack));
	stack->size = size;
	stack->top = -1;
	stack->stackArray = (int*)malloc(stack->size * sizeof(int));
	return stack;
}
int isFull(struct Stack* stack)
{
	return stack->top == stack->size - 1;
}


int isEmpty(struct Stack* stack)
{
	return stack->top == -1;
}


void push(struct Stack* stack, int value)
{
	if (isFull(stack))
		return;
	stack->stackArray[++stack->top] = value;
	printf("%d pushed to stack\n", value);
}


int pop(struct Stack* stack)
{
	if (isEmpty(stack))
		return -10000;
	return stack->stackArray[stack->top--];
}


int peek(struct Stack* stack)
{
	if (isEmpty(stack))
		return -10000;
	return stack->stackArray[stack->top];
}




struct Queue {
	struct Stack* stack1;
	struct Stack* stack2;
};


void enqueue(struct Queue* queue,int value){
	push(queue->stack1,value);
	printf("Element Inserted into Queue\n");
}
int dequeue(struct Queue* queue){
	int x, y;
	while(!isEmpty(queue->stack1)) 
	{
		// take an element out of first stack
		x = pop(queue->stack1);
		// insert it into the second stack
		push(queue->stack2,x);
	}
	y = pop(queue->stack2);
	while(!isEmpty(queue->stack2)) 
	{
		x = pop(queue->stack2);
		push(queue->stack1,x);
	}
	return y;
}




int main()
{
	
	struct Queue* queue = new Queue();
	queue->stack1 = createStack(100);
	queue->stack2 = createStack(100);
	
	enqueue(queue,10);
	enqueue(queue,100);
    enqueue(queue,1000);
    printf("Removing element from queue: %d",dequeue(queue));
	
	free(queue);
	
	getchar();
	getchar();
	return 0;
}