divisor
(src/math/divisor.hpp)

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• Last update: 2024-11-09 02:03:28+09:00
• Include: #include "src/math/divisor.hpp"

divisor

vector<ll> divisor(ll n)

正整数 $n$ の正の約数を昇順に返します．

制約

• $1 \leq n$

計算量

• $O(\sqrt{n})$

Depends on

• template (src/template/template.hpp)

Verified with

• verify/aizu_online_judge/itp1/how_many_divisors.test.cpp
• verify/unit_test/math/eratosthenes_sieve.test.cpp

Code

#pragma once
#include "../template/template.hpp"
vector<long long> divisor(const long long n) {
    assert(n >= 1);
    vector<long long> res;
    for(long long i = 1; i * i <= n; ++i) {
        if(n % i == 0) {
            res.push_back(i);
            if(i * i != n) res.emplace_back(n / i);
        }
    }
    sort(res.begin(), res.end());
    return res;
}

#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/divisor.hpp"
vector<long long> divisor(const long long n) {
    assert(n >= 1);
    vector<long long> res;
    for(long long i = 1; i * i <= n; ++i) {
        if(n % i == 0) {
            res.push_back(i);
            if(i * i != n) res.emplace_back(n / i);
        }
    }
    sort(res.begin(), res.end());
    return res;
}

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