Submission #823912

#	Time	Username	Problem	Language	Result	Execution time	Memory
823912		Sandarach151	Lutrija (COCI19_lutrija)	C++17	0 / 70	0 ms	212 KiB

lutrija

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

long long M;
long long qexp (long long b, long long e) { //quick exponentiation (see below)
    if (e == 0) return 1;
    if (e == 1) return b%M;
    long long h = qexp(b, e/2);
    h *= h;
    h %= M;
    if (e%2 == 0) return h;
    return (h*b)%M;
}
bool isPrime(long long N) {
    if (N <= 1) return 0;
    if (N <= 3) return 1;
    if (N == 4) return 0;
    long long s = (N-1)&(1-N), d = (N-1)/s;
    M = N;
    for (long long i = 0, K = 30; i < K; ++i) {
        long long witness = rand()%(N-4) + 2;  //generate random witness between [2, N-2]
        long long a = qexp(witness, d);
        if (a == 1 || a == N-1) continue;
        bool pass = 1;
        for (long long k = 1; k < s && pass; k<<=1) {
            a*=a;
            a%=N;
            if (a == N-1) pass = false;
        }
        if (pass) return 0; /* not a prime due to witness */
    }
    return 1;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    long long a, b;
    cin >> a >> b;
    bool res = true;
    vector<long long> vect;
    bool swapped = false;
    if(a%2==1 && b%2==1){
        if(a>b){
            swap(a, b);
            swapped = true;
        }
        for(int i=a; i<=b; i+=2){
            if(!isPrime(i)){
                res = false;
                break;
            }
            vect.push_back(i);
        }
    }
    else{
        if(a==2){
            swap(a, b);
            swapped = true;
        }
        if(isPrime(a) && isPrime(a+2)){
            vect.push_back(a);
            vect.push_back(a+2);
            vect.push_back(2);
        }
        else if(isPrime(a) && isPrime(a-2)){
            vect.push_back(a);
            vect.push_back(2);
        }
        else{
            res = false;
        }
    }
    if(!res){
        cout << -1 << '\n';
    }
    else{
        if(!swapped){
            cout << vect.size() << '\n';
            for(long long i=0LL; i< (long long) vect.size(); i++){
                cout << vect[i] << ' ';
            }
        }
        else{
            cout << vect.size() << '\n';
            for(long long i=vect.size()-1; i>=0; i--){
                cout << vect[i] << ' ';
            }
        }
    }
    return 0;
}

• Subtask 1: 0 / 7
• Subtask 2: 0 / 7
• Subtask 3: 0 / 7
• Subtask 4: 0 / 7
• Subtask 5: 0 / 7
• Subtask 6: 0 / 7
• Subtask 7: 0 / 7
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• Subtask 10: 0 / 7