题解 | #字母统计#开个大小为26的数组计数就行

#include <iostream>
using namespace std;
int main() {
    int counts[26]{};
    string s;
    cin >> s;
    for (char c: s) {
        if (c >= 'A' && c <= 'Z')
            counts[c - 'A']++;
    }
    for (int i = 0; i < 26; i++) {
        cout << (char) (i + 'A') << ':' << counts[i] << endl;
    }
    return 0;
}