add rivkode valid-anagram

Author: rivkode

valid-anagram/rivkode.py

@@ -1,26 +1,66 @@
 from typing import List
 
 # Time Complexity O(n log n)
-# - when sorting by sorted function(TimSort) for each string it takes O(nlogn)
-# - traversing for loop takes O(n)
+# - check len first
+# - make set for one of list for each values
+#   - if there's a duplication, then value += 1. This is a number of count.
+# - fetch value using set.get() method.
+#   - minus 1 and check if it is less than 0 which means it's invalid. return false directly.
 # Space Complexity O(n)
 # - when sorting takes O(n)
 
 class Solution:
     def isAnagram(self, s: str, t: str) -> bool:
-        s_sorted = sorted(s)
-        t_sorted = sorted(t)
 
-        for i in range(len(s_sorted)):
-            if s_sorted[i] != t_sorted[i]:
-                return False
-        return True
+        """
+        :type s: str
+        :type t: str
+        :rtype: bool
+        """
+        s_list = list(s)
+        t_list = list(t)
+
+        if len(s_list) != len(t_list):
+            return False
+
+        t_set = {}
+        for t_val in t_list:
+            cur = t_set.get(t_val, 0)
+            cur += 1
+            t_set[t_val] = cur
+            
+        
+        flag = True
+    
+        for s_val in s_list:
+            if t_set.get(s_val):
+                cur = t_set.get(s_val)
+                cur -= 1
+                t_set[s_val] = cur
+                if cur < 0:
+                    flag = False
+                    break 
+            else:
+                flag = False
+                break
+        
+        return flag
+    
+    # previous logic
+        # s_sorted = sorted(s)
+        # t_sorted = sorted(t)
+
+        # for i in range(len(s_sorted)):
+        #     if s_sorted[i] != t_sorted[i]:
+        #         return False
+        # return True
+
 
 if __name__ == "__main__":
     solution = Solution()
 
-    s = "nagaram"
-    t = "anagram"
+    s = "a"
+    t = "ab"
 
     result = solution.isAnagram(s, t)
     print(result)