Answer to Question #239591 in C for Varsha

Question

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

Answer 1

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




struct Stack {
	int top;
	unsigned size;
	int* s_Array;
};
struct Stack* createStack(unsigned size)
{
	struct Stack* stack = (struct Stack*)malloc(sizeof(struct Stack));
	stack->size = size;
	stack->top = -1;
	stack->s_Array = (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->s_Array[++stack->top] = value;
	printf("%d pushed to stack\n", value);
}




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




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








struct Queue {
	struct Stack* s1;
	struct Stack* s2;
};




void enqueue(struct Queue* queue,int value){
	push(queue->s1,value);
	printf("Element Inserted into Queue\n");
}
int dequeue(struct Queue* queue){
	int x, y;
	while(!isEmpty(queue->s1)) 
	{
		x = pop(queue->s1);
		push(queue->s2,x);
	}
	y = pop(queue->s2);
	while(!isEmpty(queue->s2)) 
	{
		x = pop(queue->s2);
		push(queue->s1,x);
	}
	return y;
}








int main()
{
	
	struct Queue* queue = new Queue();
	queue->s1 = createStack(100);
	queue->s2 = 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;
}