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ishap11 · Nov 6, 2023 · 19078bc · 19078bc
1 parent 0d3772b
commit 19078bc
Showing 1 changed file with 33 additions and 0 deletions.
diff --git a/0144-binary-tree-preorder-traversal/0144-binary-tree-preorder-traversal.java b/0144-binary-tree-preorder-traversal/0144-binary-tree-preorder-traversal.java
@@ -0,0 +1,33 @@
+/**
+ * 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;
+ *     }
+ * }
+ */
+class Solution {
+    public List<Integer> preorderTraversal(TreeNode root) {
+        List<Integer> list = new ArrayList<>();
+        Stack<TreeNode> st = new Stack<>();
+        TreeNode node = root;
+
+        while(node !=null || !st.isEmpty()){
+            while(node != null){
+                st.push(node);
+                list.add(node.val);
+                node = node.left;
+            }
+            node=st.pop();
+            node = node.right;
+        }
+        return list;
+    }
+}