System.out.println(Main28.preorderTraversal(root)); } publicstaticclassTreeNode { intval; TreeNode left; TreeNode right; TreeNode(intx) { val = x; } } //非递归 staticArrayList<Integer> array =newArrayList<>();//[4, 2, 1, 3, 6, 5, 7, 8] publicstaticArrayList<Integer> preorderT...
TreeNode(intx) { val = x; } } 第一种方法:算法实现类 importjava.util.LinkedList;importjava.util.List;publicclassSolution{privateList<Integer> result;publicList<Integer>preorderTraversal(TreeNode root){ result =newLinkedList<>(); preOrder(root);returnresult; }privatevoidpreOrder(TreeNode root)...
Preorder Traversal: Sample Solution: Java Code: classNode{intkey;Nodeleft,right;publicNode(intitem){// Constructor to create a new Node with the given itemkey=item;left=right=null;}}classBinaryTree{Noderoot;BinaryTree(){// Constructor to create an empty binary treeroot=null;}voidprint_Preo...
144.Binary Tree Preorder Traversal /*iterative*/ public List<Integer> preorderTraversal(TreeNode root) { List<Integer> result = new LinkedList<>(); if(root == null) return result; Stack<TreeNode> stack = new Stack<>(); stack.push(root); TreeNode n = root; while(!stack.isEmpty())...
binary-tree-preorder-traversal二叉树的前序遍历,代码:packagecom.niuke.p7;importjava.util.ArrayList;importjava.util.Stack;publicclassSolution{publicArrayList<Integer>preorderTraversal(Tre
empty()) return nullptr; TreeNode *root = makeNode(preorder.begin(), preorder.end(), inorder.begin(), inorder.end()); return root; } }; Java参考代码: 思路和上面一样,不过Java从数组中选择某个元素需要进行遍历(也可以转成List或者Set,但是遍历效率最高)上面C++代码中使用的是find函数。 有...
Given an array of numbers, verify whether it is the correct preorder traversal sequence of a binary search tree. You may assume each number in the sequence is unique. Follow up: Could you do it using only constant space complexity?
Approach #2: Java. /***Definitionfora binary tree node.*publicclassTreeNode{*intval;*TreeNode left;*TreeNode right;*TreeNode(intx){val=x;}*}*/classSolution{public TreeNode buildTree(int[]preorder,int[]inorder){returnhelper(0,0,inorder.length-1,preorder,inorder);}private TreeNode hel...
331. Verify Preorder Serialization of a Binary Tree One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a null node, we record using a sentinel value such as #. 代码语言:javascript 代码运行次数:...
public class Solution { public boolean isValidSerialization(String preorder) { // using a stack, scan left to right // case 1: we see a number, just push it to the stack // case 2: we see #, check i…