Building and traversing of binary tree

algo-binary-tree-traversion.js

// Node definition
function TreeNode(val) {
     this.val = val;
     this.left = this.right = null;
}

// Assemle a tree
const left = new TreeNode(2)
const right = new TreeNode(2)
const rightRight = new TreeNode(3)
const root = new TreeNode(1)

right.right = rightRight
root.left = left
root.right = right

// Traverse

// node -> left -> right
function preOrder(root){
  if(root == null){
    return
  }
  console.log(root.val)
  preOrder(root.left)
  preOrder(root.right)
}

// left -> node -> right
function inOrder(root){
  if(root == null){
    return
  }
  preOrder(root.left)
  console.log(root.val)
  preOrder(root.right)
}

// left -> right -> node
function postOrder(root){
  if(root == null){
    return
  }
  preOrder(root.left)
  preOrder(root.right)
  console.log(root.val)
}

preOrder(root)
inOrder(root)
postOrder(root)