結果

問題 No.811 約数の個数の最大化
コンテスト
ユーザー hitonanode
提出日時 2019-04-14 08:14:57
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 136 ms / 2,000 ms
コード長 4,227 bytes
コンパイル時間 1,753 ms
コンパイル使用メモリ 179,228 KB
実行使用メモリ 6,944 KB
最終ジャッジ日時 2024-09-16 06:52:01
合計ジャッジ時間 3,528 ms
ジャッジサーバーID
（参考情報） 		judge6 / judge1
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 12
権限があれば一括ダウンロードができます

ソースコード

diff # 

#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;
#define FI first
#define SE second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))

vector<int> makePrimeLst(int N)
{
    vector<int> ans;
    vector<int> alive(N+1, 1);
    lint now = 2;
    for (; now * now <= N; now++)
    {
        if (alive[now]) ans.push_back(now);
        for (int t = now; t <= N; t += now) alive[t] = 0;
    }
    for (; now <= N; now++) if (alive[now]) ans.push_back(now);
    return ans;
}


map<lint, int> primeFactorize(lint N, const vector<int> &primeLst)
{
    map<lint, int> ans;
    for (auto v : primeLst)
    {
        while (!(N % v))
        {
            N /= v;
            ans[v]++;
        }
        if (N == 1) return ans;
    }
    ans[N]++;
    return ans;
    // exit(1);
}

int n_fac(const map<lint, int> &fa)
{
    int ans = 1;
    for (auto pa : fa) ans *= pa.second + 1;
    return ans;
}

int main()
{
    int N, K;
    cin >> N >> K;
    auto primes = makePrimeLst(1000);
    map<lint, int> fa = primeFactorize(N, primes);

    int n_fac_max = 1;
    int ans = 1;
    FOR(ret, 2, N)
    {
        map<lint, int> fa2 = primeFactorize(ret, primes);
        int k = 0;
        for (auto pa : fa) k += min(fa2[pa.first], pa.second);
        if (k >= K) if (mmax(n_fac_max, n_fac(fa2))) ans = ret;
    }
    cout << ans << endl;
}
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