(Algorithms in Javascript) CTCI 3.3. Stack of Plates: Imagine a (literal) stack of plates. If the stack gets too high, it might topple. Therefore, in real life, we would likely start a new stack when the previous stack exceeds some threshold. Implement a data structure SetOfStacks that mimics this. SetOfStacks should be composed of several stack…

ctci-3.3-stack-of-plates.js

class StackOfPlates {
	constructor(capacity) {
    if(!capacity) {
      return 'Specify plate capacity. Cannot be created'; //
    }
		this._capacity = capacity;
		this._storage = [[]]; //Each array represents a set of plates
	}
	
	getLastStack(){
		return this._storage[this._storage.length-1];
	}
	
	push(element){
		if(this.getLastStack().length >= this._capacity){
			this._storage.push([]); //create new column;
		}
		this.getLastStack().push(element);
	}
	
	pop(){
		let lastStack = this.getLastStack;
		let element = lastStack().pop();
		if(lastStack().length === 0 && lastStack().length >= 1){
			this._storage.pop();
		}
		
		return element;
	}
	
	popAt(position){
		let count = 0;
		
		for(let i=0; i<this._storage.length; i++){
			for(let j=0; j<this._storage[i].length; j++){
				count++;
				if(count === position){
					let next;
					let lastElement = count();
					if(this._storage[i][j+1] && position < lastElement) {
						next = this._storage[i][j+1];
					} else if(!this._storage[i][j+1] && position !== lastElement){
						next = this._storage[i+1][0];
					}
					this._storage[i].splice(j, 1, next);
				}
				
			}
		}
	}
	
	peek() {
		return this.getLastStack()[this.getLastStack().length - 1];
  }
	
	count(){
		let m = this._storage.length() - 1; //num of rows - 1;
		let n = 0, remainder = 0;
		if(m > 1) {
			n = this._storage[this._storage.length - 2].length; 
		}
		remainder = this.getLastStack().length;
		return m*n + remainder;
	}
}