JavaScript Exercises: Middle element(s) of a stack
JavaScript Stack: Exercise-13 with Solution
Write a JavaScript program to get the middle element(s) of 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() {
return this.items[this.items.length - 1];
}
isEmpty() {
return this.items.length === 0;
}
size() {
return this.items.length;
}
getMiddleElements() {
let middleIndex = Math.floor(this.size() / 2);
let middleElements = [];
if (this.size() % 2 === 0) {
middleElements.push(this.items[middleIndex - 1]);
}
middleElements.push(this.items[middleIndex]);
return middleElements;
}
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();
}
}
let stack = new Stack();
stack.push(1);
stack.push(2);
stack.push(3);
console.log(stack.displayStack(stack));
console.log("Middle element(s):");
console.log(stack.getMiddleElements());
console.log("Add one more element:");
stack.push(4);
console.log(stack.displayStack(stack));
console.log("Middle element(s):");
console.log(stack.getMiddleElements());
console.log("Add two more elements:");
stack.push(5);
stack.push(6);
console.log(stack.displayStack(stack));
console.log("Middle element(s):");
console.log(stack.getMiddleElements());
console.log("Add one more element:");
stack.push(7);
console.log(stack.displayStack(stack));
console.log("Middle element(s):");
console.log(stack.getMiddleElements());
Sample Output:
Stack elements are: 1 2 3 Middle element(s): [2] Add one more element: Stack elements are: 1 2 3 4 Middle element(s): [2,3] Add two more elements: Stack elements are: 1 2 3 4 5 6 Middle element(s): [3,4] Add one more element: Stack elements are: 1 2 3 4 5 6 7 Middle element(s): [4]
Flowchart:
Live Demo:
See the Pen javascript-stack-exercise-13 by w3resource (@w3resource) on CodePen.
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Stack Exercises Next: Remove a specific element from a stack.
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