ttbfspreorder.js

class Node{
	constructor(val){
		this.val = val;
		this.left = null;
		this.right = null;
	}
}

class BST{
	constructor(){
		this.root = null;
	}
	insert(val){
		val = new Node(val);
		if(!this.root){
			this.root = val;
			return this;
		}
		let parent = this.root;
		let setParent = () => {
			if(val.val<parent.val && !parent.left) {parent.left = val; return;}
			if(val.val>=parent.val && !parent.right) {parent.right = val; return;}
			parent = val.val<parent.val? parent.left : parent.right;
			return setParent();
		}
		setParent();

		return this;
		
	}
	find(el){
		if(!this.root) return !!null;
		if(el === this.root.val) return this.root;
		let cur = this.root;

		let getElement = () => {
			if(cur === null) return cur = null;
			if(el === cur.val) return cur;
			if(el<cur.val) cur = cur.left;
			if(el>cur.val) cur = cur.right;
			return getElement();
		}
		getElement();

		return !!cur, cur;
	}

	bfs(){
		if(!this.root) return false;
		let result =[this.root.val];
		let que = [];

		let helper = (start = this.root) =>{
			if(start.left) {que.unshift(start.left);}
			if(start.right) {que.unshift(start.right);}
			if(que.length === 0) return result;
			
			start = que.pop();
			console.log('que pop',start.val);
			// if(start.right && start.left) que.push(start.left.val,start.right.val);
			result.push(start.val) //!start.right &&  //!start.left && 
			// console.log('this is the que:',result,'and this is the start:',(start)? start.val : null);
			return result.concat(helper(start));
		}
		helper();
		return result;

	}
	dfsPO(start = this.root){
		if(!this.root) return false;
		let result =[this.root.val];
		if(start !== this.root){
			result = [];		
		}
		
		if(!start) return result;
		if(start.left) {result.push(start.left.val);}
		if(start.right) {result.push(start.right.val);}
		
		// if(start.right && start.left) que.push(start.left.val,start.right.val);
		//!start.right &&  //!start.left && 
		// console.log('this is the que:',result,'and this is the start:',(start)? start.val : null);
		return result.concat(this.dfsPO(start.left)).concat(this.dfsPO(start.right));
	}
}



let mapple = new BST();

mapple.insert(5);
mapple.insert(7);
mapple.insert(8);
mapple.insert(3);
mapple.insert(2);
mapple.insert(1);
mapple.insert(19);
mapple.insert(20);
mapple.insert(4);
mapple.insert(6);
mapple.insert(9);


console.log(mapple);
console.log(mapple.root.left);
console.log(mapple.root.right);


console.log(mapple.dfsPO());