C Exercises: Find the top and k^th element of a stack

C Stack: Exercise-16 with Solution

Write a C program to implement a stack and accept some numeric values. Find the top and k^th element of the stack.

Sample Solution:

C Code:

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

#define MAX_SIZE 100

// Declare the stack structure
struct Stack {
    int arr[MAX_SIZE]; // Array to store elements
    int top; // Index of the top element
};

// Initialize the stack
void init_Stack(struct Stack *stack) {
    stack->top = -1; // Initialize top index to -1
}

// Check if stack is empty
int isEmpty(struct Stack *stack) { 
    return (stack->top == -1);
}

// Check if stack is full
int isFull(struct Stack *stack) {
    return (stack->top == MAX_SIZE - 1);
}

// Push an element to the stack
void push(struct Stack *stack, int value) {
    if (isFull(stack)) {
        printf("Stack is underflow!\n");
        return;
    }
    stack->arr[++stack->top] = value; // Increment top index and add element
}

// Pop an element from the stack
int pop(struct Stack *stack) {
    if (isEmpty(stack)) {
        printf("Stack is empty!\n");
        return -1;
    }
    return stack->arr[stack->top--]; // Return top element and decrement top index
}

// Get the top element of the stack
int top(struct Stack *stack) {
    if (isEmpty(stack)) {
        printf("Stack is empty\n");
        return -1;
    }
    return stack->arr[stack->top];
}

// Get the kth element from the top of the stack
int get_Kth_element_from_top(struct Stack *stack, int k) {
    if (k < 1 || k > stack->top + 1) {
        printf("Invalid value of k\n");
        return -1;
    }
    return stack->arr[stack->top - k + 1];
}

void print_stack(Stack* s) {
    if (isEmpty(s)) {
        printf("Stack is empty\n");
        return;
    }
    for (int i = 0; i <= s->top; i++) {
        printf("%d ", s->arr[i]);
    }
    printf("\n");
}

int main() {
    struct Stack stack;
    init_Stack(&stack);
    push(&stack, 1);
    push(&stack, 2);
    push(&stack, 3);
    push(&stack, 4);
    push(&stack, 5);
    push(&stack, 6);
    printf("Elements of the stack:\n");
    print_stack(&stack);
    printf("Top element: %d\n", top(&stack));
    printf("3rd element from top: %d\n", get_Kth_element_from_top(&stack, 3));
    printf("Remove the topmost element from the stack:\n");
    pop(&stack);
    printf("Elements of the stack:\n");
    print_stack(&stack);
    printf("Top element: %d\n", top(&stack));
    printf("4th element from top: %d\n", get_Kth_element_from_top(&stack, 4));
    return 0;
}

Sample Output:

Elements of the stack:
1 2 3 4 5 6
Top element: 6
3rd element from top: 4
Remove the topmost element from the stack:
Elements of the stack:
1 2 3 4 5
Top element: 5
4th element from top: 2 

Flowchart:

C Programming Code Editor:

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