is_prime
(src/math/is_prime.hpp)

• View this file on GitHub
• Last update: 2024-11-09 02:03:28+09:00
• Include: #include "src/math/is_prime.hpp"

is_prime

bool is_prime(ll n)

整数 $n$ が素数であるかどうかを返します．
$n$ が非正の場合は false を返します．

計算量

• $O(\sqrt{n})$

Depends on

• template (src/template/template.hpp)

Verified with

• verify/aizu_online_judge/alds1/prime_numbers.test.cpp
• verify/unit_test/math/eratosthenes_sieve.test.cpp

Code

#pragma once
#include "../template/template.hpp"
constexpr bool is_prime(const long long n) {
    if(n <= 1) return false;
    for(long long i = 2; i * i <= n; ++i) {
        if(n % i == 0) return false;
    }
    return true;
}

#line 2 "src/template/template.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<long long, long long>;
#define rep(i, a, b) for(long long i = (a); i < (b); ++i)
#define rrep(i, a, b) for(long long i = (a); i >= (b); --i)
constexpr long long inf = 4e18;
struct SetupIO {
    SetupIO() {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout << fixed << setprecision(30);
    }
} setup_io;
#line 3 "src/math/is_prime.hpp"
constexpr bool is_prime(const long long n) {
    if(n <= 1) return false;
    for(long long i = 2; i * i <= n; ++i) {
        if(n % i == 0) return false;
    }
    return true;
}

Back to top page