g0101_0200.s0145_binary_tree_postorder_traversal.Solution Maven / Gradle / Ivy
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Java-based LeetCode algorithm problem solutions, regularly updated
package g0101_0200.s0145_binary_tree_postorder_traversal;
// #Easy #Depth_First_Search #Tree #Binary_Tree #Stack #Data_Structure_I_Day_10_Tree
// #Udemy_Tree_Stack_Queue #2022_06_24_Time_1_ms_(49.11%)_Space_42_MB_(62.15%)
import com_github_leetcode.TreeNode;
import java.util.ArrayList;
import java.util.List;
/*
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
public class Solution {
public List postorderTraversal(TreeNode root) {
if (root == null) {
return new ArrayList<>();
}
List res = postorderTraversal(root.left);
res.addAll(postorderTraversal(root.right));
res.add(root.val);
return res;
}
}