added level order traversal questions

david-legend · david-legend · commit 6728320868a1 · 2022-09-12T15:32:32.000Z
diff --git a/leetcode/src/binary_trees/lc_102_binary_tree_level_order_traversal/binary_tree_level_order_traversal.py b/leetcode/src/binary_trees/lc_102_binary_tree_level_order_traversal/binary_tree_level_order_traversal.py
@@ -0,0 +1,21 @@
+from collections import deque
+
+def level_order_traversal(root):
+    if not root:
+            return []
+        
+    result = []
+    queue = deque([root])
+    while queue:
+        level_size, data = len(queue), []
+        for _ in range(level_size):
+            curr_node = queue.popleft()
+            data.append(curr_node.val)
+            if curr_node.left:
+                queue.append(curr_node.left)
+            if curr_node.right:
+                queue.append(curr_node.right)
+                
+        result.append(data)
+    
+    return result
diff --git a/leetcode/src/binary_trees/lc_103_binary_tree_zigzag_level_order_traversal/binary_tree_zigzag_level_order_traversal.py b/leetcode/src/binary_trees/lc_103_binary_tree_zigzag_level_order_traversal/binary_tree_zigzag_level_order_traversal.py
@@ -0,0 +1,29 @@
+from collections import deque
+
+def zigzag_level_order(root):
+    result = []
+    if not root:
+        return result
+    
+    queue = deque([root])
+    left_to_right = True
+    
+    while queue:
+        level_size, data = len(queue), deque()
+        for _ in range(level_size):
+            curr_node = queue.popleft()
+            
+            if left_to_right:
+                data.append(curr_node.val)
+            else:
+                data.appendleft(curr_node.val)
+            
+            if curr_node.left:
+                queue.append(curr_node.left)
+            if curr_node.right:
+                queue.append(curr_node.right)
+                
+        result.append(data)
+        left_to_right = not left_to_right
+    
+    return result
diff --git a/leetcode/src/binary_trees/lc_107_binary_tree_level_order_traversal_II/binary_tree_level_order_traversal.py b/leetcode/src/binary_trees/lc_107_binary_tree_level_order_traversal_II/binary_tree_level_order_traversal.py
@@ -0,0 +1,23 @@
+from collections import deque
+
+def level_order_bottom(root):
+    if not root:
+            return []
+        
+    result = deque()
+    queue = deque([root])
+    while queue:
+        level_size, level_data = len(queue), []
+        for _ in range(level_size):
+            curr_node = queue.popleft()
+            level_data.append(curr_node.val)
+            
+            if curr_node.left:
+                queue.append(curr_node.left)
+            
+            if curr_node.right:
+                queue.append(curr_node.right)
+                
+        result.appendleft(level_data)
+    
+    return result
