First Unique Character in a String

First Unique Character in a String

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

Examples:

s = "leetcode"
return 0.

s = "loveleetcode"
return 2.

 

Note: You may assume the string contains only lowercase English letters.

 

 

class Solution {
public:
    int firstUniqChar(string s) {
        int dp[26]={0};
        for(auto ch: s)
        {
            dp[ch-'a']++;
        }
        for(int i=0;i<s.size();++i)
            if(dp[s[i]-'a']==1)
                return i;
        return -1;
    }
};