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Solution.java
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Solution.java
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package g0501_0600.s0589_n_ary_tree_preorder_traversal;
// #Easy #Depth_First_Search #Tree #Stack #Programming_Skills_I_Day_5_Function #Level_1_Day_6_Tree
// #2022_08_25_Time_1_ms_(90.98%)_Space_45.4_MB_(83.13%)
import com_github_leetcode.Node;
import java.util.ArrayList;
import java.util.List;
/*
// Definition for a Node.
class Node {
public int val;
public List<Node> neighbors;
public Node() {}
public Node(int _val) {
val = _val;
}
public Node(int _val, List<Node> _neighbors) {
val = _val;
neighbors = _neighbors;
}
};
*/
public class Solution {
public List<Integer> preorder(Node root) {
List<Integer> res = new ArrayList<>();
preorderHelper(res, root);
return res;
}
private void preorderHelper(List<Integer> res, Node root) {
if (root == null) {
return;
}
res.add(root.val);
for (Node node : root.neighbors) {
preorderHelper(res, node);
}
}
}