JavaScript Exercises: Find elements that are common in two stacks

JavaScript Stack: Exercise-28 with Solution

Common Elements in Two Stacks

Write a JavaScript program that implements a stack and finds elements that are common in two stacks..

Sample Solution:

JavaScript Code:

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

  // push element to the stack
  push(element) {
    this.items.push(element);
  }

  // pop element from the stack
  pop() {
    if (this.items.length == 0) {
      return "Underflow";
    }
    return this.items.pop();
  }

  // get the top element of the stack
  peek() {
    return this.items[this.items.length - 1];
  }

  // check if the stack is empty
  isEmpty() {
    return this.items.length == 0;
  }

  // get the size of the stack
  size() {
    return this.items.length;
  }

  // intersect the stack with another stack
  intersect(stk) {
    let intersection = new Stack();

    // Stack elements in a loop
    for (let i = 0; i < this.items.length; i++) {
      let item = this.items[i];

      // Push the item to the new stack if the other stack contains it
      if (stk.items.indexOf(item) != -1) {
        intersection.push(item);
      }
    }
    return intersection;
  }
 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();
 }
}
const stack1 = new Stack();
stack1.push(1);
stack1.push(2);
stack1.push(3);
console.log("Stack1:");
console.log(stack1.displayStack(stack1));
const stack2 = new Stack();
stack2.push(2);
stack2.push(3);
console.log("Stack2:");
console.log(stack2.displayStack(stack2));
const stack3 = new Stack();
stack3.push(1);
stack3.push(2);
console.log("Stack3:");
console.log(stack3.displayStack(stack3));
let result = stack1.intersect(stack2);
console.log("Common elements of stack1 and stack2!");
console.log(result.displayStack(result));
result = stack1.intersect(stack3);
console.log("Common elements of stack1 and stack3!");
console.log(result.displayStack(result));
result = stack2.intersect(stack3);
console.log("Common elements of stack2 and stack3!");
console.log(result.displayStack(result));

Sample Output:

 "Stack1:"
"Stack elements are:"
"1 2 3"
"Stack2:"
"Stack elements are:"
"2 3"
"Stack3:"
"Stack elements are:"
"1 2"
"Common elements of stack1 and stack2!"
"Stack elements are:"
"2 3"
"Common elements of stack1 and stack3!"
"Stack elements are:"
"1 2"
"Common elements of stack2 and stack3!"
"Stack elements are:"
"2"

Flowchart:

Live Demo:

See the Pen javascript-stack-exercise-28 by w3resource (@w3resource) on CodePen.

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Stack Exercises Next: Stack elements in the first but not in the second.