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C++中居然有和python字典一样的东西

unordered_map（无序）、map （有序）

先计算所有字母的频数，用unordered_map映射存储；接着，遍历str，找出unordered_map中value为1的key

class Solution {
public:
    int FirstNotRepeatingChar(string str) {
        if(str.size() == 0) return -1;
        unordered_map<char, int> countMap; 
        for(int i = 0;i < str.size();i++){
            countMap[str[i]]++; 
        }
        int pos = -1;
        for(int i = 0;i < str.size();i++){
            if(countMap[str[i]] == 1){
                pos = i;
                break;
            }
        }
        return pos;          
    }
};

python实现：

# -*- coding:utf-8 -*-
class Solution:
    def FirstNotRepeatingChar(self, s):
        if s == "":
            return -1
        count = {}
        for i in s:
            if i in count:
                count[i] += 1;
            else:
                count[i] = 1
        for index,item in enumerate(s):#取s的下标和值
            if count[item] == 1:
                return index