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Solution.java
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Solution.java
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package g0001_0100.s0094_binary_tree_inorder_traversal;
// #Easy #Top_100_Liked_Questions #Top_Interview_Questions #Depth_First_Search #Tree #Binary_Tree
// #Stack #Data_Structure_I_Day_10_Tree #Udemy_Tree_Stack_Queue #Big_O_Time_O(n)_Space_O(n)
// #2022_06_21_Time_0_ms_(100.00%)_Space_42.7_MB_(9.33%)
import com_github_leetcode.TreeNode;
import java.util.ArrayList;
import java.util.Collections;
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<Integer> inorderTraversal(TreeNode root) {
if (root == null) {
return Collections.emptyList();
}
List<Integer> answer = new ArrayList<>();
inorderTraversal(root, answer);
return answer;
}
public void inorderTraversal(TreeNode root, List<Integer> answer) {
if (root == null) {
return;
}
if (root.left != null) {
inorderTraversal(root.left, answer);
}
answer.add(root.val);
if (root.right != null) {
inorderTraversal(root.right, answer);
}
}
}