144. Binary Tree Preorder Traversal
- Binary Tree Preorder Traversal:题目链接
方法1：递归遍历
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| /**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public List<Integer> preorderTraversal(TreeNode root) {
ArrayList<Integer> array = new ArrayList<Integer>();
preorderTraversal( root , array);
return array;
}
public void preorderTraversal(TreeNode root, List<Integer> array) {
if (root != null) {
array.add(root.val);
preorderTraversal(root.left, array);
preorderTraversal(root.right, array);
}
}
}
|
