题解 | 计算某字符出现次数

#include <cctype>
#include <iostream>
#include <bits/stdc++.h>
using namespace std;

int main() {
    unordered_map<char, int> mp;
    string input;
    getline(cin, input);
    for(auto c: input) {
        if(isdigit(c)) {
            mp[c]++;
        } else if(isalpha(c)) {
            mp[tolower(c)]++;
        }
    }

   char c;
   cin >> c;
    cout << mp[tolower(c)]<< endl;
}
// 64 位输出请用 printf("%lld")