zoj2562 More Divisors

#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<cstring>
#include<iomanip>
using namespace std;
typedef long long i64;
#define out64 "%lld\n"
#define in64 "%lld"
/************ for topcoder by zz1215 *******************/
#define FOR(i,a,b)      for( int i = (a) ; i <= (b) ; i ++)
#define FFF(i,a)        for( int i = 0 ; i < (a) ; i ++)
#define FFD(i,a,b)      for( int i = (a) ; i >= (b) ; i --)
#define S64(a)          scanf(in64,&a)
#define SS(a)           scanf("%d",&a)
#define LL(a)           ((a)<<1)
#define RR(a)           (((a)<<1)+1)
#define pb              push_back
#define CL(Q)           while(!Q.empty())Q.pop()
#define MM(name,what)   memset(name,what,sizeof(name))
#define read            freopen("in.txt","r",stdin)
#define write           freopen("out.txt","w",stdout)

const int inf = 0x3f3f3f3f;
const i64 inf64 = 0x3f3f3f3f3f3f3f3fLL;
const double oo = 10e9;
const double eps = 10e-9;
const double pi = acos(-1.0);
const i64 maxn = 10000000000000000LL;

struct zz
{
    i64 x;
    i64 n;
    bool operator < (const zz & cmp ) const
    {
        return x < cmp.x;
    }
}zx;

vector<i64>p;
vector<zz>vx;
vector<i64>v;

bool isp(i64 x)
{
    i64 temp = sqrt(x);
    for(int i=0;i<p.size();i++)
    {
        if(p[i]>temp)  return true;

        if(!(x%p[i]))  return false;
    }
    return true;
}

void init()
{
    p.clear();
    p.pb(2);
    for(int i=3;i<100;i++)
    {
        if(isp(i))
        {
            p.pb(i);
        }
    }
    return ;
}

void dfs(i64 rest,i64 id=0,i64 pre=inf,i64 x=1,i64 n=1)
{
    if(id>16) return ;
    if(rest == 0)
    {
        zx.x = x;
        zx.n = n;
        vx.pb(zx);
        return ;
    }
    i64 temp;
    bool ok;
    for(int i=min(pre,rest);i>=1;i--)
    {
        temp = x;
        ok = true;
        for(int u=1;u<=i;u++)
        {
            temp *= p[id];
            if(temp > maxn)
            {
                ok = false;
                break;
            }
        }
        if(!ok) continue;
        dfs(rest-i,id+1,i,temp,n*(i+1));
    }
    return ;
}

void start()
{
    for(int i=0;i<30;i++)
    {
        dfs(i);
    }

    sort(vx.begin(),vx.end());

    i64 temp = 0;
    v.clear();

    for(int i=0;i<vx.size();i++)
    {
        if(vx[i].n <= temp)
        {
            continue;
        }
        else
        {
            temp = vx[i].n;
            v.pb(vx[i].x);
        }
    }
    v.pb(inf64);
    return ;
}

i64 n;

i64 find()
{
    int l = 0;
    int r = v.size()-1;
    int mid;
    while(l<r)
    {
        mid = (l+r+1)/2;
        if(v[mid] < n)
        {
            l = mid;
        }
        else if(v[mid]>n)
        {
            r = mid-1;
        }
        else
        {
            return v[mid];
        }
    }
    return v[l];
}

int main()
{
    init();

    start();

    while(cin>>n)
    {
        cout<<find()<<endl;
    }
    return 0;
}