cousins_in_a_binary_tree.py

data_structures/binary_tree/cousins_in_a_Binary_Tree.py

@@ -0,0 +1,51 @@
+from collections import deque
+
+
+class Node:
+    def __init__(self, val):
+        self.val = val
+        self.left = None
+        self.right = None
+
+
+def are_cousins(root, x, y):
+    if not root:
+        return False
+
+    queue = deque([(root, None)])  # (node, parent)
+
+    while queue:
+        size = len(queue)
+        x_parent = y_parent = None
+
+        for _ in range(size):
+            node, parent = queue.popleft()
+
+            if node.val == x:
+                x_parent = parent
+            if node.val == y:
+                y_parent = parent
+
+            if node.left:
+                queue.append((node.left, node))
+            if node.right:
+                queue.append((node.right, node))
+
+        # After one level is processed
+        if x_parent and y_parent:
+            return x_parent != y_parent  # True if different parents
+        if (x_parent and not y_parent) or (y_parent and not x_parent):
+            return False  # Found one but not the other
+
+    return False
+
+
+# 🔹 Example Usage:
+root = Node(1)
+root.left = Node(2)
+root.right = Node(3)
+root.left.left = Node(4)
+root.right.right = Node(5)
+
+print("Are 4 and 5 cousins?", are_cousins(root, 4, 5))  # ✅ True
+print("Are 2 and 3 cousins?", are_cousins(root, 2, 3))  # ❌ False