JavaScript Exercises: Sort the elements of a stack in descending order

JavaScript Stack: Exercise-2 with Solution

Sort Stack Descending

Write a JavaScript program to sort the elements of a given stack in descending order.

Sample Solution:

JavaScript Code:

class Stack {
  constructor() {
    this.items = [];
  }
  
  // Pushes an element onto the stack
  push(element) {
    this.items.push(element);
  }
  
  // Removes the top element from the stack and returns it
  pop() {
    if (this.items.length == 0)
      return "Underflow";
    return this.items.pop();
  }
  
  // Checks if the stack is empty
  isEmpty() {
    return this.items.length == 0;
  }
  
 // Returns the top element of the stack
  peek() {
    if (this.items.length == 0)
      return "No elements in Stack";
    return this.items[this.items.length - 1];
  }

 displayStack(stack) {
   console.log("Stack elements are:");
   let str = "";
   for (let i = 0; i < stack.items.length; i++)
     str += stack.items[i] + " ";
   return str.trim();
  }
  
 sort_Stack(stack) {
  // Create a temporary stack to hold sorted elements
  let tempStack = new Stack();
  
  while (!stack.isEmpty()) {
    // Pop the top element from the original stack
    let currentElement = stack.pop();
    
    // Move all elements greater than currentElement from tempStack back to stack
    while (!tempStack.isEmpty() && tempStack.peek() > currentElement) {
      stack.push(tempStack.pop());
    }
    
    // Push the currentElement onto the tempStack
    tempStack.push(currentElement);
  }
  
  // Move all elements from tempStack back to stack
  while (!tempStack.isEmpty()) {
    stack.push(tempStack.pop());
  }  
  return stack;
 }   
}
console.log("Initialize a stack:")
let stack = new Stack();
console.log("Input some elements on the stack:")
stack.push(1);
stack.push(4);
stack.push(3);
stack.push(2);
stack.push(5);
console.log(stack.displayStack(stack));
stack.sort_Stack(stack);
console.log("Sort the elements of the stack in descending order:")
console.log(stack.displayStack(stack));
console.log("Remove one element and insert two elements:")
stack.pop();
stack.push(0);
stack.push(8);
console.log(stack.displayStack(stack));
stack.sort_Stack(stack);
console.log("Sort the elements of the stack in descending order:")
console.log(stack.displayStack(stack));

Sample Output:

Initialize a stack:
Input some elements on the stack:
Stack elements are:
1 4 3 2 5
Sort the elements of the stack in descending order:
Stack elements are:
5 4 3 2 1
Remove one element and insert two elements:
Stack elements are:
5 4 3 2 0 8
Sort the elements of the stack in descending order:
Stack elements are:
8 5 4 3 2 0

Flowchart:

Live Demo:

See the Pen javascript-stack-exercise-2 by w3resource (@w3resource) on CodePen.

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