【14】387. First Unique Character in a String

387. First Unique Character in a String

Total Accepted: 41662

• Total Submissions: 91486
• Difficulty: Easy
• Contributors: Admin

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.

class Solution {
public:
    int firstUniqChar(string s) {
        unordered_map<char, int> hash;
        for(char c : s){
            hash[c]++;
        }
        /*
        for(int i : hash){
            if(i == 1)
        }*///没法从hash表里判断，因为只知道value不能逆向得知hash里面的key
        //所以要从原string里找
        for(int i = 0; i < s.size(); i++){
            if(hash[s[i]] == 1){
                return i;
            }
        }
        return -1;
    }
};