test: migrate LeetCode 1684 to new directory structure with tests and docs

README.md

@@ -41,11 +41,11 @@ Each problem follows this structure:
 
 ## Solutions
 
-📊 **Statistics**: 84 problems solved (migrated to new structure)
+📊 **Statistics**: 85 problems solved (migrated to new structure)
 
 | Difficulty | Count |
 |------------|-------|
-| Easy       | 59    |
+| Easy       | 60    |
 | Medium     | 24    |
 | Hard       | 1     |
 

docs/EASY.md

@@ -1,6 +1,6 @@
 # Easy Problems
 
-Total: 59 problems solved
+Total: 60 problems solved
 
 ## Solutions
 
@@ -46,6 +46,7 @@ Total: 59 problems solved
 | 1603 | [Design Parking System](https://leetcode.com/problems/design-parking-system/) | [solution.py](../problems/easy/design_parking_system_1603/solution.py) | [test_solution.py](../problems/easy/design_parking_system_1603/test_solution.py) |
 | 1662 | [Check If Two String Arrays Are Equivalent](https://leetcode.com/problems/check-if-two-string-arrays-are-equivalent/) | [solution.py](../problems/easy/check_if_two_string_arrays_are_equivalent_1662/solution.py) | [test_solution.py](../problems/easy/check_if_two_string_arrays_are_equivalent_1662/test_solution.py) |
 | 1672 | [Richest Customer Wealth](https://leetcode.com/problems/richest-customer-wealth/) | [solution.py](../problems/easy/richest_customer_wealth_1672/solution.py) | [test_solution.py](../problems/easy/richest_customer_wealth_1672/test_solution.py) |
+| 1684 | [Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings/) | [solution.py](../problems/easy/count_the_number_of_consistent_strings_1684/solution.py) | [test_solution.py](../problems/easy/count_the_number_of_consistent_strings_1684/test_solution.py) |
 | 1773 | [Count Items Matching a Rule](https://leetcode.com/problems/count-items-matching-a-rule/) | [solution.py](../problems/easy/count_items_matching_a_rule_1773/solution.py) | [test_solution.py](../problems/easy/count_items_matching_a_rule_1773/test_solution.py) |
 | 1816 | [Truncate Sentence](https://leetcode.com/problems/truncate-sentence/) | [solution.py](../problems/easy/truncate_sentence_1816/solution.py) | [test_solution.py](../problems/easy/truncate_sentence_1816/test_solution.py) |
 | 1929 | [Concatenation of Array](https://leetcode.com/problems/concatenation-of-array/) | [solution.py](../problems/easy/concatenation_of_array_1929/solution.py) | [test_solution.py](../problems/easy/concatenation_of_array_1929/test_solution.py) |

problems/easy/count_the_number_of_consistent_strings_1684/solution.py

@@ -0,0 +1,31 @@
+# Tags: Array, String, Hash Table
+from typing import List
+
+
+class Solution:
+    def count_consistent_strings(self, allowed: str, words: List[str]) -> int:
+        """
+        Let A be the length of allowed string, and L be the total number of characters across all words.
+
+        Time complexity: O(A + L)
+        - Creating the set from allowed: O(A)
+        - Iterating through all words and characters: O(L) total
+        - Each set lookup (c not in allowed_set) is O(1) on average
+        - Overall: O(A) + O(L) = O(A + L)
+
+        Space complexity: O(A)
+        - The allowed_set set stores at most A unique characters from allowed
+        - Other variables (res, is_consistent) use O(1) constant space
+        - Overall: O(A)
+        """
+        allowed_set = set(allowed)
+        res = 0
+        for word in words:
+            is_consistent = True
+            for c in word:
+                if c not in allowed_set:
+                    is_consistent = False
+                    break
+            if is_consistent:
+                res += 1
+        return res

problems/easy/count_the_number_of_consistent_strings_1684/test_solution.py

@@ -0,0 +1,15 @@
+import pytest
+from tests.base_test import BaseTestSolution
+from .solution import Solution
+
+
+class TestSolution(BaseTestSolution):
+    solution = Solution()
+
+    @pytest.mark.parametrize("method_name, allowed, words, expected, timeout", [
+        ('count_consistent_strings', "ab", ["ad", "bd", "aaab", "baa", "badab"], 2, None),
+        ('count_consistent_strings', "abc", ["a", "b", "c", "ab", "ac", "bc", "abc"], 7, None),
+        ('count_consistent_strings', "cad", ["cc", "acd", "b", "ba", "bac", "bad", "ac", "d"], 4, None),
+    ])
+    def test_count_consistent_strings(self, method_name, allowed, words, expected, timeout):
+        self._run_test(self.solution, method_name, (allowed, words,), expected, timeout)