JS 二叉树

JS二叉树的实现及前序遍历、中序遍历、后序遍历

// 二叉树的实现
  function Node(data, left, right) {
    this.data = data;
    this.left = left;
    this.right = right;
    this.show = () => {
      return this.data;
    };
  }

  function BST() {
    this.root = null;
    this.insert = insert; // 插入节点方法
    this.preOrder = preOrder;
    this.inOrder = inOrder;
    this.postOrder = postOrder;
  }

  function insert(n) {
    let node = new Node(n, null, null);
    if (this.root === null) {
      this.root = node;
    } else {
      let current = this.root;
      while (true) {
        if (n < current.data) {
          if (current.left == null) {
            current.left = node;
            break;
          }
          current = current.left;
        } else {
          if (current.right == null) {
            current.right = node;
            break;
          }
          current = current.right;
        }
      }
    }
  }

  var bst = new BST();
  var nums = [10, 3, 18, 2, 4, 13, 21, 9, 8, 9];
  for (var i = 0; i < nums.length; i++) {
    bst.insert(nums[i]);
  }
  console.log("树结构", bst);
  bst.preOrder(bst.root);
  //   bst.inOrder(bst.root);
  //   bst.postOrder(bst.root);

  // 前序遍历：父节点 -> 左节点 -> 右节点
  function preOrder(node) {
    if (node !== null) {
      console.log(node.show() + " ");
      preOrder(node.left);
      preOrder(node.right);
    }
  }
  // 10 -> 3 -> 2 -> 4 -> 9 -> 8 -> 9 -> 18 -> 13 -> 21

  // 中序遍历：左节点 -> 父节点 -> 右节点
  function inOrder() {
    if (node !== null) {
      inOrder(node.left);
      console.log(node.show() + " ");
      inOrder(node.right);
    }
  }
  // 2 -> 3 -> 4 -> 8 -> 9 -> 9 -> 10 -> 13 -> 18 -> 21

  // 后序遍历：左节点 -> 右节点 -> 父节点
  function postOrder() {
    if (node !== null) {
      postOrder(node.left);
      postOrder(node.right);
      console.log(node.show() + " ");
    }
  }
  // 2 -> 8 -> 9 -> 9 -> 4 -> 3 -> 13 -> 21 -> 18 -> 10