diff --git a/src/stack/decode_string/__init__.py b/src/stack/decode_string/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/stack/decode_string/solution.py b/src/stack/decode_string/solution.py
new file mode 100644
index 0000000..6ac71ff
--- /dev/null
+++ b/src/stack/decode_string/solution.py
@@ -0,0 +1,20 @@
+class Solution:
+    def decodeString(self, s: str) -> str:
+        stack = []
+        number = []
+
+        for char in s:
+            if char.isdigit():
+                number.append(char)
+            elif char == '[':
+                stack.append("".join(number))
+                number = []
+            elif char == ']':
+                alphas = []
+                while stack[-1].isalpha():
+                    alphas.append(stack.pop())
+                stack.extend(reversed(alphas * int(stack.pop())))
+            else:
+                stack.append(char)
+
+        return "".join(stack)
diff --git a/tests/test_decode_string.py b/tests/test_decode_string.py
new file mode 100644
index 0000000..1fe9e85
--- /dev/null
+++ b/tests/test_decode_string.py
@@ -0,0 +1,17 @@
+import pytest
+from src.stack.decode_string.solution import (
+    Solution,
+)
+
+
+@pytest.mark.parametrize(
+    "s, expected",
+    [
+        ("3[a]2[bc]", "aaabcbc"),
+        ("3[a2[c]]", "accaccacc"),
+        ("2[abc]3[cd]ef", "abcabccdcdcdef"),
+    ],
+)
+def test_decode_string(s, expected):
+    solution = Solution()
+    assert solution.decodeString(s) == expected