C++ :

#include <iostream>
using namespace std;
int main() {
    int age;
    cin >> age;
    switch (age / 10) {
        case 0: case 1:
            if (age <= 12) cout << "儿童";
            else cout << "青少年";
            break;
        case 2: case 3: case 4: case 5: case 6:
            if (age < 65) cout << "成人";
            else cout << "老年人";
            break;
        case 7: case 8: case 9: case 10: case 11: case 12:
            cout << "老年人";
            break;
        default:
            cout << "输入无效";
    }
    return 0;
}