test/aoj/ALDS1_1_C.is_prime.test.cpp

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• Last update: 2024-01-08 17:31:43+09:00
• Problem: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_1_C

Depends on

• Prime Number Algorithms (math/number-theory/prime.hpp)

Code

#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_1_C"

#include "../../math/number-theory/prime.hpp"

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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;
    int ans = 0;
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;
        if (is_prime(a)) ans++;
    }
    cout << ans << endl;
}

#line 1 "test/aoj/ALDS1_1_C.is_prime.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_1_C"

#line 2 "math/number-theory/prime.hpp"
#include <map>
#include <numeric>
#include <vector>

/*
 * Primality Test
 */
bool is_prime(long long n) {
    if (n <= 1) return false;
    if (n <= 3) return true;
    if (n % 2 == 0 || n % 3 == 0) return false;
    if (n < 9) return true;
    for (long long i = 5; i * i <= n; i += 6) {
        if (n % i == 0 || n % (i + 2) == 0) return false;
    }
    return true;
}

/*
 * Prime Table
 */
std::vector<bool> prime_table(int n) {
    std::vector<bool> prime(n + 1, true);
    prime[0] = prime[1] = false;
    for (int j = 4; j <= n; j += 2) prime[j] = false;
    for (int i = 3; i * i <= n; i += 2) {
        if (!prime[i]) continue;
        for (int j = i * i; j <= n; j += 2 * i) prime[j] = false;
    }
    return prime;
}

/*
 * Table of Minimum Prime Factors
 */
std::vector<int> min_factor_table(int n) {
    std::vector<int> factor(n + 1);
    std::iota(factor.begin(), factor.end(), 0);
    for (int i = 2; i * i <= n; ++i) {
        if (factor[i] != i) continue;
        for (int j = i * i; j <= n; j += i) {
            if (factor[j] == j) factor[j] = i;
        }
    }
    return factor;
}

/*
 * Prime Factorization
 */
std::map<long long, int> prime_factor(long long n) {
    std::map<long long, int> ret;
    if (n % 2 == 0) {
        int cnt = 0;
        while (n % 2 == 0) {
            ++cnt;
            n /= 2;
        }
        ret[2] = cnt;
    }
    for (long long i = 3; i * i <= n; i += 2) {
        if (n % i == 0) {
            int cnt = 0;
            while (n % i == 0) {
                ++cnt;
                n /= i;
            }
            ret[i] = cnt;
        }
    }
    if (n != 1) ret[n] = 1;
    return ret;
}
#line 4 "test/aoj/ALDS1_1_C.is_prime.test.cpp"

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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;
    int ans = 0;
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;
        if (is_prime(a)) ans++;
    }
    cout << ans << endl;
}

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