Add num of ways to split a string

Author: agpeshal

Diff for: strings/num_splits.py

@@ -0,0 +1,44 @@
+"""
+You are given a string s, a split is called good if you can split s into
+2 non-empty strings p and q where its concatenation is equal to s and
+the number of distinct letters in p and q are the same.
+
+Return the number of good splits you can make in s. 
+"""
+from collections import Counter, defaultdict
+
+def num_splits(self, s: str):
+        """
+        >> num_splits("aacaba")
+        2
+        >> num_splits("abcd")
+        1
+        >> num_splits("aaaaa")
+        4
+        """
+        ans = 0
+        rightSplit = Counter(s)
+        leftSplit = defaultdict(int)
+        
+        leftCount = 0
+        rightCount = len(rightSplit)
+        
+        for ch in s:
+            rightSplit[ch] -= 1
+            leftSplit[ch] += 1
+            
+            if rightSplit[ch] == 0:
+                rightCount -= 1
+            
+            leftCount = len(leftSplit)
+            
+            if leftCount == rightCount:
+                ans += 1
+        
+        return ans
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()