unordered_map<char,int>
字符个数统计
https://www.nowcoder.com/practice/eb94f6a5b2ba49c6ac72d40b5ce95f50
#include <iostream>
#include <string>
#include <unordered_map>
using namespace std;
int main() {
char c;
unordered_map<char, int> mp;
while (cin >> c) {
mp[c]++;
}
cout << mp.size() << endl;
return 0;
}
