leetcode387

public class Solution {
    public int FirstUniqChar(string s) {
        Dictionary<char, int> dic = new Dictionary<char, int>();
            foreach (char c in s)
            {
                if (!dic.ContainsKey(c))
                {
                    dic.Add(c, 1);
                }
                else
                {
                    dic[c]++;
                }
            }

            var list = dic.Where(x => x.Value == 1).ToList();

            var index = -1;

            for (int i = 0; i < s.Length; i++)
            {
                var c = s[i];
                if (list.Any(x => x.Key == c))
                {
                    index = i;
                    break;
                }
            }
            Console.WriteLine(index);
            return index;
    }
}

https://leetcode.com/problems/first-unique-character-in-a-string/#/description

 

补充一个python的实现：

import collections

class Solution:
    def firstUniqChar(self, s: str) -> int:        
        dic = collections.OrderedDict()#有序字典
        for i in range(len(s)):#遍历字符串
            c = s[i]#当前字符
            if c not in dic:#第一次出现，key是字符，value是一个二元组[字符频率,字符索引]
                dic[c] = [1,i]
            else:
                dic[c][0] += 1#出现多次，key是字符，value二元组修改，字符频率+1
                dic[c][1] = -1#字符索设定为-1，表示此字符不符合题目要求
        for _,v in dic.items():#dic有序
            if v[0] == 1:#字符出现了一次
                return v[1]#返回对应的索引
        return -1