博客

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[]}
 */
var inorderTraversal = function(root) {
    const  arr=[];
    const inorder = function(root){
         if(root === null){return}
         if(root.left !== null){ 
             inorder(root.left); 
             }
           arr.push(root.val)
           console.log('root.val',root.val)
         if(root.right !=null){ 
             inorder(root.right); 
             }
           
   }
    //别忘记调用
            inorder(root)
           return arr

};

迭代，调用函数，if判断