StringReversalUsingStack_Mruganka.cpp

/*Given an array arr[] of size N, the task to reverse the array using Stack.*/

// C program to implement
// the above approach
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
// Structure of stack
struct Stack {
 
    // Stores index of top
    // element of a stack
    int top;
 
    // Stores maximum count of
    // elements stored in a stack
    unsigned capacity;
 
    // Stores address of
    // array element
    int* array;
};
 
// Function to Initialize a stack
// of given capacity.
struct Stack* createStack(unsigned capacity)
{
    struct Stack* stack
        = (struct Stack*)malloc(
            sizeof(struct Stack));
    stack->capacity = capacity;
    stack->top = -1;
    stack->array
        = (int*)malloc(
            stack->capacity
            * sizeof(int));
    return stack;
}
 
// Function to check if
// the stack is full or not
int isFull(struct Stack* stack)
{
    return stack->top
        == stack->capacity - 1;
}
 
// Function to check if
// the stack is empty or not
int isEmpty(struct Stack* stack)
{
    return stack->top == -1;
}
 
// Function to insert an element
// into the stack.
void push(struct Stack* stack, int item)
{
 
    // If stack is full
    if (isFull(stack))
        return;
 
    // Insert element into stack
    stack->array[++stack->top] = item;
}
 
// Function to remove an element
// from stack.
int pop(struct Stack* stack)
{
 
    // If stack is empty
    if (isEmpty(stack))
        return -1;
 
    // Pop element from stack
    return stack->array[stack->top--];
}
 
// Function to reverse the array elements
void reverseArray(int arr[], int n)
{
 
    // Initialize a stack of capacity n
    struct Stack* stack = createStack(n);
 
    for (int i = 0; i < n; i++) {
 
        // Insert arr[i] into the stack
        push(stack, arr[i]);
    }
 
    // Reverse the array elements
    for (int i = 0; i < n; i++) {
 
        // Update arr[i]
        arr[i] = pop(stack);
    }
 
    // Print array elements
    for (int i = 0; i < n; i++)
        printf("%d ", arr[i]);
}
 
// Driver Code
int main()
{
 
    int arr[] = { 100, 200, 300, 400 };
 
    int N = sizeof(arr) / sizeof(arr[0]);
    reverseArray(arr, N);
    return 0;
}