[Leetcode]First Unique Character in a String

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

Examples:

s = "leetcode"
return 0.

s = "loveleetcode",
return 2.

Note: You may assume the string contain only lowercase letters.

Subscribe to see which companies asked this question

class Solution {
public:
/*algoritm two pass
1)first pass book count of char
2)second pass get the first
O(n)
*/
int firstUniqChar(string s) {
int count[26]={0};
for(int i = 0;i < s.size();i++){
count[s[i]-'a']++;
}
for(int i = 0;i < s.size();i++){
if(count[s[i]-'a']==1)return i;
}
return -1;
}
};