387. First Unique Character in a String

Easy
​
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
Example 2:
Input: s = "loveleetcode"
Output:
2
Example 3:
Input: s = "aabb"
Output:
-1
Constraints:
  • 1 <= s.length <= 105
  • s consists of only lowercase English letters.

解題

Runtime: 9 ms, faster than 93.92%
Memory Usage: 5.4 MB, less than 78.65%
func firstUniqChar(s string) int {
arr := make([]int, 26)
for i := 0; i < len(s); i++ {
arr[s[i] - 'a']++
}
for i := 0; i < len(s); i++ {
if arr[s[i] - 'a'] == 1 {
return i
}
}
return -1
}