let BST = function(value,name){
  this.value = value
  this.name = name
  this.children = [
  ]
} 

BST.prototype.insert = function(value,name){

  if(!this.children){
    this.children = []
  }
  
  if(value < this.value){
    if(!this.children[0]){
      this.children[0] = new BST(value,name)
    }else if(this.children[0].value == null){
      this.children[0] = new BST(value,name)
    }else{
      this.children[0].insert(value,name)
    }
  }else if(value > this.value){ 
    if(!this.children[1]){
      if(this.children.length == 0){
        this.children[0] = new BST(null)
      }
      this.children[1] = new BST(value,name)
    }else{
      this.children[1].insert(value,name)
    }
  }
}

BST.prototype.depthFirstTraversal = function(order, length = 1,queue = []){
	if(!this.children){
    this.children = []
  }

  if(order == 'pre-order'){
	  queue.push(this.id)
	  length--   	
  }

  if(this.children[0] && this.children[0].value != null){
    length++
    this.children[0].depthFirstTraversal(order,length,queue)
  }


  if(order === 'in-order'){
	  queue.push(this.id)
	  length-- 
  }

  if(this.children[1]){
    length++
    this.children[1].depthFirstTraversal(order,length,queue)
  }

  if(order == 'post-order'){
	  queue.push(this.id)
	  length--   	
  }

  return queue
  
}