Easy
First Unique Character
Easy
275 submissions
10 coins
+50 XP
Hash Table
String
Problem Description
Return the index of the first character in `s` that appears exactly once. If every character repeats, return `-1`.
**Example 1:**
```
Input: s = "compilemate"
Output: 0
```
**Example 2:**
```
Input: s = "aabbc"
Output: 4
```
**Example 3:**
```
Input: s = "aabb"
Output: -1
```
Constraints
- `1 <= s.length <= 10^5`
- Lowercase English letters only.
Need help?
Connect with expert programmers for real-time collaborative coding, video meetings, and whiteboard sessions via CodeConnect.
Video Call
Whiteboard
Live Coding
Screen Share