Merge pull request #16 from codewithme-py/feat/find-all-anagrams-in-a-string-0438

problem solution & test 0438

Author: codewithme-py

problems_cache.json

@@ -19293,5 +19293,35 @@
     "Count Subarrays With K Distinct Integers",
     "Hard",
     "count-subarrays-with-k-distinct-integers"
+  ],
+  "4241": [
+    "Unique Email Groups",
+    "Medium",
+    "unique-email-groups"
+  ],
+  "4247": [
+    "Minimum Capacity Box",
+    "Easy",
+    "minimum-capacity-box"
+  ],
+  "4240": [
+    "Find the Smallest Balanced Index",
+    "Medium",
+    "find-the-smallest-balanced-index"
+  ],
+  "4220": [
+    "Minimum Operations to Sort a String",
+    "Medium",
+    "minimum-operations-to-sort-a-string"
+  ],
+  "4192": [
+    "Minimum Cost to Partition a Binary String",
+    "Hard",
+    "minimum-cost-to-partition-a-binary-string"
+  ],
+  "4261": [
+    "Reverse K Subarrays",
+    "Medium",
+    "reverse-k-subarrays"
   ]
 }

solutions/find_all_anagrams_in_a_string_0438.py

@@ -0,0 +1,27 @@
+from collections import Counter
+
+
+class Solution:
+    def findAnagrams(self, s: str, p: str) -> list[int]:
+        """
+        Finds all the initial anagram indexes of the p line in the s line.
+        An anagram is a permutation of the letters of the string p.
+        For example, 'ab' and 'ba' are anagrams.
+        The algorithm uses a sliding window of fixed size len(p)
+        And a dictionary for counting characters in the current window
+        and in the reference line p.
+        This allows you to compare the window with p for O(1) (on average),
+        reaching Total time O(n), where n is the length of the string s.
+        """
+        if len(p) > len(s):
+            return []
+        p_count, window_count, result = Counter(p), Counter(), []
+        for i in range(len(s)):
+            window_count[s[i]] += 1
+            if i >= len(p):
+                window_count[s[i - len(p)]] -= 1
+                if window_count[s[i - len(p)]] == 0:
+                    del window_count[s[i - len(p)]]
+            if window_count == p_count:
+                result.append(i - len(p) + 1)
+        return result

tests/test_find_all_anagrams_in_a_string_0438.py

@@ -0,0 +1,13 @@
+import pytest
+
+from solutions.find_all_anagrams_in_a_string_0438 import Solution
+
+
+@pytest.mark.parametrize('s, p, expected', [
+    ('cbaebabacd', 'abc', [0, 6]),
+    ('abab', 'ab', [0, 1, 2]),
+    ('ab', 'ab', [0]),
+])
+def test_solution(s: str, p: str, expected: list[int]) -> None:
+    sol = Solution()
+    assert sol.findAnagrams(s, p) == expected