Add 'Binary Tree Right Side View'

Author: nickolashkraus

README.md

@@ -10,6 +10,8 @@ A collection of LeetCode solutions
 
 [Binary Tree Level Order Traversal](./src/binary_tree_level_order_traversal.py)
 
+[Binary Tree Right Side View](./src/binary_tree_right_side_view.py)
+
 [Climbing Stairs](./src/climbing_stairs.py)
 
 [Coin Change](./src/coin_change.py)

src/binary_tree_right_side_view.py

@@ -0,0 +1,35 @@
+"""
+199. Binary Tree Right Side View
+
+https://leetcode.com/problems/binary-tree-right-side-view
+
+NOTES
+  * If you haven't already, solve 'Binary Tree Level Order Traversal'. Using
+    the breadth-first approach, the solution is trivial.
+"""
+
+from collections import deque
+
+from src.classes import TreeNode
+
+
+class Solution:
+    def rightSideView(self, root: TreeNode | None) -> list[int]:
+        if not root:
+            return []
+
+        nodes: list[int] = []
+        queue: deque[TreeNode] = deque([root])
+
+        while queue:
+            width = len(queue)
+            for i in range(width):
+                curr = queue.popleft()
+                if i == width - 1:
+                    nodes.append(curr.val)
+                if curr.left:
+                    queue.append(curr.left)
+                if curr.right:
+                    queue.append(curr.right)
+
+        return nodes

tests/test_binary_tree_right_side_view.py

@@ -0,0 +1,32 @@
+"""
+199. Binary Tree Right Side View
+
+https://leetcode.com/problems/binary-tree-right-side-view
+"""
+
+from unittest import TestCase
+
+from src.binary_tree_right_side_view import Solution
+from tests.utils import create_binary_tree_from_list
+
+
+class TestSolution(TestCase):
+    def test_1(self):
+        exp = [1, 3, 4]
+        root = create_binary_tree_from_list([1, 2, 3, None, 5, None, 4])
+        assert Solution().rightSideView(root) == exp
+
+    def test_2(self):
+        exp = [1, 3, 4, 5]
+        root = create_binary_tree_from_list([1, 2, 3, 4, None, None, None, 5])
+        assert Solution().rightSideView(root) == exp
+
+    def test_3(self):
+        exp = [1, 3]
+        root = create_binary_tree_from_list([1, None, 3])
+        assert Solution().rightSideView(root) == exp
+
+    def test_4(self):
+        exp = []
+        root = create_binary_tree_from_list([])
+        assert Solution().rightSideView(root) == exp