feat(Reverse String): From LeetCode (#28)

features/problems/leetcode/easy/Reverse String.feature

@@ -0,0 +1,20 @@
+Feature: Reverse String
+
+  # SRC: https://leetcode.com/problems/reverse-string/
+
+  # Constraints
+  # - 1 <= s.length <= 105
+  # - s[i] is a printable ascii character.
+
+
+  Scenario Outline: _
+    Given an array of <chars>
+    When I call reverseString
+    Then the void function returns None
+    And the same array is procedurally <reversed> by reference
+#   And it used 0(1) extra memory # TODO how to test?
+
+  Examples:
+  |    chars    |  reversed   |
+  |   h,e,l,l,o | o,l,l,e,h   |
+  | H,a,n,n,a,h | h,a,n,n,a,H |

src/problems/__main__.py

@@ -9,6 +9,7 @@
 from src.problems.interviews.shortest_common_prefixes import __main__ as shortest_common_prefixes
 from src.problems.leetcode.easy.longest_common_prefix import __main__ as longest_common_prefix
 from src.problems.leetcode.easy.palindrome_number import __main__ as palindrome_number
+from src.problems.leetcode.easy.reverse_string import __main__ as reverse_string
 from src.problems.leetcode.easy.roman_to_integer import __main__ as roman_to_integer
 from src.problems.leetcode.easy.two_sum import __main__ as two_sum
 from src.problems.leetcode.easy.valid_parentheses import __main__ as valid_parentheses
@@ -26,6 +27,7 @@
     shortest_common_prefixes,
     longest_common_prefix,
     palindrome_number,
+    reverse_string,
     roman_to_integer,
     two_sum,
     valid_parentheses,

src/problems/leetcode/easy/reverse_string/README.md

@@ -0,0 +1,26 @@
+# 344. Reverse String
+
+Write a function that reverses a string. The input string is given as an array of characters `s`.
+
+You must do this by modifying the input array in-place with `O(1)` extra memory.
+
+## Examples
+
+### Example 1
+
+- Input: s = ["h","e","l","l","o"]
+- Output: ["o","l","l","e","h"]
+
+### Example 2
+
+- Input: s = ["H","a","n","n","a","h"]
+- Output: ["h","a","n","n","a","H"]
+
+### Constraints
+
+- `1 <= s.length <= 105`
+- `s[i]` is a printable ascii character.
+
+## SRC
+
+[344. Reverse String](https://leetcode.com/problems/reverse-string/description/)

src/problems/leetcode/easy/reverse_string/__init__.py

@@ -0,0 +1,5 @@
+from .v1 import Solution, solution
+
+reverse_string = solution.reverseString
+
+__all__ = ["Solution", "solution", "reverse_string"]

src/problems/leetcode/easy/reverse_string/__main__.py

@@ -0,0 +1,31 @@
+from typing import Optional
+
+from hamcrest import assert_that, equal_to
+
+from src.problems.leetcode.easy.reverse_string import reverse_string
+
+
+def test(chars: list[str], expected: Optional[list[str]] = None) -> None:
+    reverse_string(chars)
+    actual_string: str = "".join(chars)
+    expected_string: str = "".join(expected or [])
+    assert_that(actual_string, equal_to(expected_string))
+    print("✅", end="")
+
+
+def run() -> None:
+    # Example 1:
+    # Input: s = ['h','e','l','l','o']
+    # Output: ['o','l','l','e','h']
+    test(["h", "e", "l", "l", "o"], expected=["o", "l", "l", "e", "h"])
+
+    # Example 2:
+    # Input: s = ['H', 'a', 'n', 'n', 'a', 'h']
+    # Output: ['h', 'a', 'n', 'n', 'a', 'H']
+    test(["H", "a", "n", "n", "a", "h"], expected=["h", "a", "n", "n", "a", "H"])
+
+    print("\n")
+
+
+if __name__ == "__main__":
+    run()

src/problems/leetcode/easy/reverse_string/protocol.py

@@ -0,0 +1,25 @@
+from typing import Protocol, runtime_checkable
+
+"""
+SRC: https://leetcode.com/problems/reverse-string/
+
+Write a function that reverses a string.
+The input string is given as an array of characters s.
+You must do this by modifying the input array in-place with O(1) extra memory.
+"""
+
+
+@runtime_checkable  # NOTE: Allows for isinstance check.
+class SolutionProtocol(Protocol):
+    def reverseString(self, s: list[str]) -> None:
+        """
+        SolutionProtocol.reverseString
+
+        Given an array of characters s, it modifies the same array.
+
+        Parameters:
+          - `s` (`list[str]`): An array of string characters.
+
+        Returns: `None`
+        """
+        raise NotImplementedError

src/problems/leetcode/easy/reverse_string/v1.py

@@ -0,0 +1,24 @@
+from src.problems.leetcode.easy.reverse_string.protocol import SolutionProtocol
+
+
+class Solution:  # (SolutionProtocol)
+    def reverseString(self, s: list[str]) -> None:
+        """
+        SolutionProtocol.reverseString
+
+        Given an array of characters s, it modifies the same array.
+
+        Parameters:
+          - `s` (`list[str]`): An array of string characters.
+
+        Returns: `None`
+        """
+
+        chars = s
+        # FIXME simplify do 1 trip, instead of 2
+        inverted = chars[::-1]
+        for idx, item in enumerate(inverted):
+            s[idx] = item  # type: ignore
+
+
+solution: SolutionProtocol = Solution()

tests/step_defs/problems/leetcode/easy/test__reverse_string.py

@@ -0,0 +1,34 @@
+from hamcrest import assert_that, equal_to, is_
+from pytest_bdd import given, parsers, scenarios, then, when
+
+from src.problems.leetcode.easy.reverse_string import reverse_string
+
+scenarios("problems/leetcode/easy/Reverse String.feature")
+
+
+@given(parsers.parse("an array of {chars}"), converters={"chars": lambda s: s.split(",")}, target_fixture="context")
+def given_an_array_of_chars(chars):
+    return {"chars": chars}
+
+
+@when("I call reverseString")
+def when_I_call_reverseString(context):
+    chars = context["chars"]
+    copy = list(chars)
+    context["result"] = reverse_string(copy)
+    context["reversed"] = copy
+
+
+@then("the void function returns None")
+def then_it_returns_None(context):
+    result = context["result"]
+    assert_that(result, is_(None))
+
+
+@then(
+    parsers.parse("the same array is procedurally {expected} by reference"),
+    converters={"expected": lambda s: s.split(",")},
+)
+def then_the_string_got_reversed(expected, context):
+    actual = context["reversed"]
+    assert_that(expected, equal_to(actual))