【題解】ZeroJudge d442: 10591 – Happy Number

#include <iostream>
#include <set>
using namespace std;

int main() {
    int T, Case=1;
    long long N, tmp;
    cin >> T;
    while (T--){
        cin >> N;
        cout << "Case #" << Case++ << ": " << N;
        set<long long> st;
        while (N != 1){
            if (st.count(N)){
                break;
            }
            st.insert(N);
            tmp = 0;
            while (N >= 10){
                tmp += (N % 10) * (N % 10);
                N /= 10;
            }
            tmp += N*N;
            N = tmp;
        }
        if (N == 1) cout << " is a Happy number.\n";
        else cout << " is an Unhappy number.\n";
    }
    return 0;
}

T = int(input())

for TC in range(1, T+1):
    N = int(input())
    print(f"Case #{TC}: {N} ", end="")
    st = set()
    while N != 1:
        if N in st:
            break
        st.add(N)
        tmp = 0
        while N >= 10:
            tmp += (N % 10) ** 2
            N //= 10
        tmp += N * N
        N = tmp
    if N == 1:
        print("is a Happy number.")
    else:
        print("is an Unhappy number.")