Submission #349289

#	Time	Username	Problem	Language	Result	Execution time	Memory
349289		denkendoemeer	Boat (APIO16_boat)	C++14	100 / 100	1451 ms	4480 KiB

boat

#include<bits/stdc++.h>
#define ll long long
using namespace std;
#define mod 1000000007
vector<int>aux;
array<int,2>v[505];
ll dp[1005][505],inv[505];
int main()
{
    //freopen(".in","r",stdin);
    //freopen(".out","w",stdout);
    int n,i,j,e;
    scanf("%d",&n);
    aux={-1};
    inv[1]=1;
    for(i=2;i<=n;i++)
        inv[i]=(mod-mod/i)*inv[mod%i]%mod;
    for(i=1;i<=n;i++){
        scanf("%d%d",&v[i][0],&v[i][1]);
        ++v[i][1];
        aux.push_back(v[i][0]);
        aux.push_back(v[i][1]);
    }
    sort(aux.begin(),aux.end());
    aux.resize(unique(aux.begin(),aux.end())-aux.begin());
    int m=aux.size();
    for(i=0;i<m;i++)
        dp[i][0]=1;
    for(i=1;i<=n;i++){
        for(j=m-1;j>=1;j--)
            if (v[i][0]<=aux[j-1] && aux[j]<=v[i][1]){
                int cnt=aux[j]-aux[j-1];
                for(e=min(cnt,i);e>=1;e--)
                    dp[j][e]=(dp[j][e]+dp[j][e-1]*(cnt-e+1)%mod*inv[e])%mod;
            }
        for(j=1;j<=m;j++){
            dp[j][0]=0;
            for(e=0;e<=n;e++)
                dp[j][0]=(dp[j][0]+dp[j-1][e])%mod;
        }
    }
    printf("%lld\n",(dp[m][0]+mod-1)%mod);
return 0;
}

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:13:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   13 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
boat.cpp:19:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   19 |         scanf("%d%d",&v[i][0],&v[i][1]);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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