25th Anton and Letters

a.题目链接

https://codeforces.com/problemset/problem/443/A

b. 我的做法

#include <vector>
#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
	vector<int>a(26, 0);
	string s;
	getline(cin, s);
	for(int i = 0; i < s.length(); i++){
		if(s[i] <= 'z' && s[i] >= 'a')a[s[i] - 97]++;
	}
	
	int cnt = 0;
	for(int i = 0; i < 26; i++){
		if(a[i])cnt++; 
	}
	
	cout << cnt << endl;
	return 0;
}