Java: New stack from a portion of the original stack

Last update on December 21 2024 09:42:59 (UTC/GMT +8 hours)

Write a Java program that implements a stack and creates a new stack from a portion of the original stack.

Sample Solution:

Java Code:

import java.util.Scanner;

public class Stack {
  private int[] arr;
  private int top;

  // Constructor to initialize the stack
  public Stack(int size) {
    arr = new int[size];
    top = -1;
  }

  // Method to push an element onto the stack
  public void push(int num) {
    if (top == arr.length - 1) {
      System.out.println("Stack is full");
    } else {
      top++;
      arr[top] = num;
    }
  }

  // Method to pop an element from the stack
  public int pop() {
    if (top == -1) {
      System.out.println("Stack Underflow");
      return -1;
    } else {
      int poppedElement = arr[top];
      top--;
      return poppedElement;
    }
  }

  // Method to get the top element of the stack
  public int peek() {
    if (top == -1) {
      System.out.println("Stack is empty");
      return -1;
    } else {
      return arr[top];
    }
  }

  // Method to check if the stack is empty
  public boolean isEmpty() {
    return top == -1;
  }

  // Method to get the size of the stack
  public int getSize() {
    return top + 1;
  }

  // Method to create SubStack
  public Stack slice(int start, int end) {
    if (start < 0 || end >= arr.length || start > end) {
      System.out.println("Invalid indices");
      return null;
    }

    int newSize = end - start + 1;
    Stack subStack = new Stack(newSize);

    for (int i = start; i <= end; i++) {
      subStack.push(arr[i]);
    }

    return subStack;
  }

  // Method to display the elements of the stack
  public void display() {
    if (top == -1) {
      System.out.println("Stack is empty!");
    } else {
      System.out.print("Stack elements: ");
      for (int i = top; i >= 0; i--) {
        System.out.print(arr[i] + " ");
      }
      System.out.println();
    }
  }

  public static void main(String[] args) {

    Stack stack1 = new Stack(8);
    Stack result = new Stack(8);
    stack1.push(1);
    stack1.push(2);
    stack1.push(3);
    stack1.push(4);
    stack1.push(5);
    stack1.push(6);
    stack1.push(7);
    stack1.push(8);
    System.out.println("Original Stack:");
    stack1.display();
    System.out.println("\nExtract a portion from the said stack:");
    int index_pos1 = 1;
    int index_pos2 = 3;
    System.out.println("\nIndex Position1 = " + index_pos1 + " Index Position2 = " + index_pos2);
    result = stack1.slice(index_pos1, index_pos2);
    result.display();
    index_pos1 = 3;
    index_pos2 = 7;
    System.out.println("\nIndex Position1 = " + index_pos1 + " Index Position2 = " + index_pos2);
    result = stack1.slice(index_pos1, index_pos2);
    result.display();
  }
}

Sample Output:

Original Stack:
Stack elements: 8 7 6 5 4 3 2 1

Extract a portion from the said stack:

Index Position1 = 1 Index Position2 = 3
Stack elements: 4 3 2

Index Position1 = 3 Index Position2 = 7
Stack elements: 8 7 6 5 4

Flowchart:

Live Demo:

Java Code Editor:

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