leetcode 387. 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.

本题题意很简单，就是寻找第一个不重复的元素，先做一遍统计，然后遍历即可得到答案

下面是C++的做法，

代码如下：

#include <iostream>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <stack>
#include <string>
#include <climits>
#include <algorithm>
#include <sstream>
#include <functional>
#include <bitset>
#include <numeric>
#include <cmath>
#include <regex>

using namespace std;


class Solution 
{
public:
    int firstUniqChar(string s) 
    {
        vector<int> count(26, 0);
        for (char c : s)
            count[c - 'a']++;
        for (int i = 0; i < s.length(); i++)
        {
            if (count[s[i] - 'a'] == 1)
                return i;
        }
        return -1;
    }
};