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JavaScript Exercises: Remove duplicates from a given stack

JavaScript Stack: Exercise-9 with Solution

Write a JavaScript program to remove duplicates from a given stack.

Sample Solution:

JavaScript Code:

class Stack {
  constructor() {
    this.items = [];
  }

  push(element) {
    this.items.push(element);
  }
  pop() {
    if (this.isEmpty())
      return "Underflow";
    return this.items.pop();
  }
  peek() {
    if (this.isEmpty())
      return "No elements in Stack";
    return this.items[this.items.length - 1];
  }
  isEmpty() {
    return this.items.length === 0;
  }
removeDuplicates() {
    const uniqueItems = [];
    const seen = new Set();
    for (let i = 0; i < this.items.length; i++) {
      const currentItem = this.items[i];
      if (!seen.has(currentItem)) {
        uniqueItems.push(currentItem);
        seen.add(currentItem);
      }
    }
    this.items = uniqueItems;
  }
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();
 }        
}
console.log("Initialize a stack:")
let stack = new Stack();
console.log("Input some elements on the stack:")
stack.push(1);
stack.push(6);
stack.push(3);
stack.push(2);
stack.push(5);
stack.push(6); 
console.log(stack.displayStack(stack));
stack.removeDuplicates();
console.log("After removing duplicates from the said stack:");
console.log(stack.displayStack(stack));
console.log("Input two more elements on the stack:")
stack.push(1);
stack.push(6);
console.log(stack.displayStack(stack));
stack.removeDuplicates();
console.log("After removing duplicates from the said stack:");
console.log(stack.displayStack(stack));

Sample Output:

Initialize a stack:
Input some elements on the stack:
Stack elements are:
1 6 3 2 5 6
After removing duplicates from the said stack:
Stack elements are:
1 6 3 2 5
Input two more elements on the stack:
Stack elements are:
1 6 3 2 5 1 6
After removing duplicates from the said stack:
Stack elements are:
1 6 3 2 5

Flowchart:

Flowchart: JavaScript  Exercises: Remove duplicates from a given stack .
Flowchart: JavaScript  Exercises: Remove duplicates from a given stack .
Flowchart: JavaScript  Exercises: Remove duplicates from a given stack .

Live Demo:

See the Pen javascript-stack-exercise-8 by w3resource (@w3resource) on CodePen.


Improve this sample solution and post your code through Disqus

Stack Previous: Check if an element is present or not in a stack.
Stack Exercises Next: Top and bottom elements of a stack.

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JavaScript: Tips of the Day

Creates an array of elements, ungrouping the elements in an array produced by zip and applying the provided function

Example:

const tips_unzip = (arr, fn) =>
  arr
    .reduce(
      (acc, val) => (val.forEach((v, i) => acc[i].push(v)), acc),
      Array.from({
        length: Math.max(...arr.map(x => x.length))
      }).map(x => [])
    )
    .map(val => fn(...val));

console.log(tips_unzip([[2, 15, 200], [3, 25, 300]], (...args) => args.reduce((acc, v) => acc + v, 0)));

Output:

[5, 40, 500]