Submission #257962

#	Time	Username	Problem	Language	Result	Execution time	Memory
257962		daniel920712	Boat (APIO16_boat)	C++14	0 / 100	2085 ms	4636 KiB

boat

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <set>
#include <map>
#include <time.h>

using namespace std;
long long MOD=1e9+7;
map < pair < long long , long long > , long long > all;
long long N;
long long a[505],b[505];
map < long long , long long > con,r;
set < long long > have;
long long Pow(long long a,long long b)
{
    if(b==0) return a;
    long long t=Pow(a,b/2);
    t*=t;
    t%=MOD;
    if(b%2) t*=a;
    return t%MOD;
}
long long F(long long x,long long y)
{
    long long i,j,now;
    if(x==0) return y!=(1e9+5);
    if(all.find(make_pair(x,y))!=all.end()) return all[make_pair(x,y)];
    all[make_pair(x,y)]=F(x-1,y);
    for(auto i:con)
    {
        if(i.first>=a[x]&&r[i.first]<y&&r[i.first]<=b[x])
        {

            now=1;
            for(j=x;j>=1;j--)
            {
                if(i.first>=a[j]&&r[i.first]<y&&r[i.first]<=b[j])
                {
                    now*=(i.second-(x-j));
                    now%=MOD;
                    now*=Pow(x-j+1,MOD-2);
                    now%=MOD;
                    all[make_pair(x,y)]+=now*F(j-1,i.first)%MOD;
                    all[make_pair(x,y)]%=MOD;

                }
                else break;
            }

        }
    }
    return all[make_pair(x,y)];
}
long long F2(long long x,long long y)
{
    long long i;
    //printf("%lld %lld\n",x,y);
    if(x==0) return y!=1e9+5;
    if(all.find(make_pair(x,y))!=all.end()) return all[make_pair(x,y)];
    all[make_pair(x,y)]=F2(x-1,y);
    for(i=a[x];i<=min(b[x],y-1);i++)
    {

        all[make_pair(x,y)]+=F2(x-1,i);

        all[make_pair(x,y)]%=MOD;
    }

    return all[make_pair(x,y)];
}
int main()
{
    //freopen("3_01.in","rt",stdin);
    //srand(time(NULL));
    long long N,M,i;
    scanf("%lld",&N);
    for(i=1;i<=N;i++)
    {
        scanf("%lld %lld",&a[i],&b[i]);
        //b[i]=rand()%100;
        //a[i]=rand()%100;
        //if(a[i]>b[i]) swap(a[i],b[i]);
        //printf("%lld %lld\n",a[i],b[i]);
        have.insert(a[i]);
        have.insert(a[i]+1);
        have.insert(b[i]);
        have.insert(b[i]+1);
    }
    for(auto i:have)
    {
        if(i==*prev(have.end()))
        {
            con[i]=1;
            r[i]=i;
        }
        //printf("%lld %lld\n",*prev(have.lower_bound(i)),i);
        if(have.lower_bound(i)!=have.begin())
        {
            con[*prev(have.lower_bound(i))]=i-*prev(have.lower_bound(i));
            r[*prev(have.lower_bound(i))]=i-1;
        }
    }
    printf("%lld\n",F(N,1e9+5));


    return 0;
}
/*
2
32 47
18 78
*/

Compilation message (stderr)

boat.cpp: In function 'long long int F(long long int, long long int)':
boat.cpp:26:15: warning: unused variable 'i' [-Wunused-variable]
     long long i,j,now;
               ^
boat.cpp: In function 'int main()':
boat.cpp:76:17: warning: unused variable 'M' [-Wunused-variable]
     long long N,M,i;
                 ^
boat.cpp:77:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&N);
     ~~~~~^~~~~~~~~~~
boat.cpp:80:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld %lld",&a[i],&b[i]);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42