Create stack_using_queue.c

C/stack_using_queue.c

@@ -0,0 +1,108 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define MAX 100  // Maximum size of the stack
+
+// Stack structure definition
+struct Stack {
+    int arr[MAX];
+    int top;
+};
+
+// Initialize the stack
+void initStack(struct Stack* s) {
+    s->top = -1;
+}
+
+// Check if the stack is empty
+int isEmpty(struct Stack* s) {
+    return s->top == -1;
+}
+
+// Check if the stack is full
+int isFull(struct Stack* s) {
+    return s->top == MAX - 1;
+}
+
+// Push an element onto the stack
+void push(struct Stack* s, int data) {
+    if (isFull(s)) {
+        printf("Stack Overflow\n");
+        return;
+    }
+    s->arr[++(s->top)] = data;
+}
+
+// Pop an element from the stack
+int pop(struct Stack* s) {
+    if (isEmpty(s)) {
+        printf("Stack Underflow\n");
+        exit(1);
+    }
+    return s->arr[(s->top)--];
+}
+
+// Peek the top element of the stack
+int peek(struct Stack* s) {
+    if (isEmpty(s)) {
+        printf("Stack is empty\n");
+        exit(1);
+    }
+    return s->arr[s->top];
+}
+
+// Queue structure using two stacks
+struct Queue {
+    struct Stack s1, s2;  // Two stacks for enqueue and dequeue
+};
+
+// Initialize the queue
+void initQueue(struct Queue* q) {
+    initStack(&q->s1);
+    initStack(&q->s2);
+}
+
+// Enqueue operation
+void enqueue(struct Queue* q, int data) {
+    // Push the data into the first stack
+    push(&q->s1, data);
+    printf("Enqueued %d\n", data);
+}
+
+// Dequeue operation
+int dequeue(struct Queue* q) {
+    // If the second stack is empty, transfer elements from the first stack
+    if (isEmpty(&q->s2)) {
+        while (!isEmpty(&q->s1)) {
+            push(&q->s2, pop(&q->s1));
+        }
+    }
+    // Pop the top element from the second stack
+    if (!isEmpty(&q->s2)) {
+        int data = pop(&q->s2);
+        printf("Dequeued %d\n", data);
+        return data;
+    } else {
+        printf("Queue is empty\n");
+        exit(1);
+    }
+}
+
+int main() {
+    struct Queue q;
+    initQueue(&q);
+
+    enqueue(&q, 10);
+    enqueue(&q, 20);
+    enqueue(&q, 30);
+
+    dequeue(&q);
+    dequeue(&q);
+
+    enqueue(&q, 40);
+
+    dequeue(&q);
+    dequeue(&q);
+
+    return 0;
+}