feat(work): add solution for LeetCode 387 First Unique Character in a String

work/3/Easy/Hash Table/387.first-unique-character-in-a-string.py

@@ -0,0 +1,54 @@
+"""
+387. First Unique Character in a String
+Difficulty: Easy
+https://leetcode.com/problems/first-unique-character-in-a-string/
+
+──────────────────────────────────────────────────
+
+Given a string s, find the first non-repeating character in it and
+return its index. If it does not exist, return -1.
+
+
+
+Example 1:
+
+Input: s = "leetcode"
+
+Output: 0
+
+Explanation:
+
+The character 'l' at index 0 is the first character that does not
+occur at any other index.
+
+Example 2:
+
+Input: s = "loveleetcode"
+
+Output: 2
+
+Example 3:
+
+Input: s = "aabb"
+
+Output: -1
+
+
+
+Constraints:
+
+        • 1 <= s.length <= 10^5
+
+        • s consists of only lowercase English letters.
+"""
+
+from collections import Counter
+
+
+class Solution:
+    def firstUniqChar(self, s: str) -> int:
+        map = Counter(s)
+        for i, c in enumerate(s):
+            if map[c] == 1:
+                return i
+        return -1