Week 14: 102. Binary Tree Level Order Traversal Solution

Author: doh6077

binary-tree-level-order-traversal/doh6077.py

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+from collections import deque
+# 102. Binary Tree Level Order Traversal
+class Solution:
+    def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]:
+        # 1. Edge Case: Empty Tree
+        if not root:
+            return [] 
+        
+        result = [] 
+        queue = deque([root])
+        
+        while queue:
+            # 2. Capture the number of nodes at the current level
+            level_size = len(queue)
+            current_level_nodes = []
+            
+            for _ in range(level_size):
+                current_node = queue.popleft()
+                current_level_nodes.append(current_node.val)
+                
+                # 3. Add children to the queue for the NEXT level
+                if current_node.left:
+                    queue.append(current_node.left)
+                if current_node.right: 
+                    queue.append(current_node.right)
+            
+            # Add the finished level to our result
+            result.append(current_level_nodes)
+            
+        return result