"K-th Symbol in Grammar" solution

src/k_th_symbol_in_grammar.py

@@ -0,0 +1,20 @@
+class Solution:
+    def kthGrammar(self, n: int, k: int) -> int:
+        total = 2 ** (n - 1)
+        current = 0
+
+        while k > 2:
+            half = total // 2
+
+            if k > half:
+                k -= half
+                current = 0 if current else 1
+            else:
+                current = 1 if current else 0
+
+            total = half
+
+        if current:
+            return 1 if k == 1 else 0
+        else:
+            return 1 if k == 2 else 0

tests/test_k_th_symbol_in_grammar.py

@@ -0,0 +1,16 @@
+import pytest
+
+from src.k_th_symbol_in_grammar import Solution
+
+
+@pytest.mark.parametrize(
+    "n,k,expected",
+    (
+        (1, 1, 0),
+        (2, 1, 0),
+        (2, 2, 1),
+        (3, 3, 1),
+    ),
+)
+def test_solution(n, k, expected):
+    assert Solution().kthGrammar(n, k) == expected