Added a new code

strings/permutation_in_string.py

@@ -0,0 +1,30 @@
+from collections import Counter
+
+class Solution:
+    def check_inclusion(self, s1: str, s2: str) -> bool:
+        n1, n2 = len(s1), len(s2)
+        if n2 < n1:
+            return False
+        freq1, freq2 = Counter(s1), Counter(s2[0:n1])
+        if freq1 == freq2:
+            return True
+        left, right = 1, n1
+        while right < n2:
+            freq2[s2[left-1]] -= 1
+            if freq2[s2[left-1]] == 0:
+                del freq2[s2[left-1]]  # Remove characters with zero frequency
+            freq2[s2[right]] += 1
+            if freq1 == freq2:
+                return True
+            right += 1
+            left += 1
+        return False
+
+# Test the function
+if __name__ == "__main__":
+    s1 = "ab"
+    s2 = "eidbaooo"
+
+    sol = Solution()
+    result = sol.check_inclusion(s1, s2)
+    print(result)  # Should return True or False based on the input strings