Binary Tree Inorder Traversal(转)

2024-01-17 22:18:04

Given a binary tree, return the inorder traversal of its nodes' values.

For example: Given binary tree {1,#,2,3},

return [1,3,2].

/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public List<Integer> inorderTraversal(TreeNode root) {
List<Integer> res = new ArrayList<>();
dfs(root, res);
return res;
}
private void dfs(TreeNode root, List<Integer> res) {
if (root != null) {
dfs(root.left, res);
res.add(root.val);
dfs(root.right, res);
}
}
}

/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public List<Integer> inorderTraversal(TreeNode root) {
List<Integer> res = new ArrayList<>();
if (root == null) {
return res;
}
LinkedList<TreeNode> stack = new LinkedList<>();
while (root!=null || !stack.isEmpty()) {
if (root!=null) {
stack.push(root);
root = root.left;
} else {
root = stack.pop();
res.add(root.val);
root = root.right;
}
}
return res;
}
}

http://hcx2013.iteye.com/blog/2230218