Create 387-first_unique_character_in_str.py

Author: stevestar888

387-first_unique_character_in_str.py

@@ -0,0 +1,41 @@
+"""
+https://leetcode.com/problems/first-unique-character-in-a-string/submissions/
+"""
+class Solution(object):
+    
+    """
+    Brute force
+    
+    Runtime: not very good
+    """
+    def firstUniqChar(self, str):
+        """
+        :type s: str
+        :rtype: int
+        """
+        for s in str:
+            if str.count(s) == 1:
+                return str.index(s)
+        return -1
+    
+    """
+    O(n) solution--using dictionary-equivalent DS
+    
+    Runtime: 136 ms, faster than 65.45% of Python online submissions for First Unique Character in a String.
+    Memory Usage: 13 MB, less than 85.64% of Python online submissions for First Unique Character in a String.
+    """
+    def firstUniqChar(self, str):
+        """
+        :type s: str
+        :rtype: int
+        """
+        counts = [0] * 26
+        
+        #find counts for each
+        for s in str:
+            counts[ord(s) - ord('a')] += 1
+            
+        for i, s in enumerate(str):
+            if counts[ord(s) - ord('a')] == 1:
+                return i
+        return -1