Submission #400058

#	Time	Username	Problem	Language	Result	Execution time	Memory
400058		juggernaut	Boat (APIO16_boat)	C++17	100 / 100	1444 ms	4296 KiB

boat

#include<bits/stdc++.h>
#define fr first
#define sc second
using namespace std;
void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
typedef long long ll;
#define USING_ORDERED_SET 0
#if USING_ORDERED_SET
#include<bits/extc++.h>
using namespace __gnu_pbds;
template<class T>using ordered_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
#endif
template<class T>void umax(T &a,T b){if(a<b)a=b;}
template<class T>void umin(T &a,T b){if(b<a)a=b;}
#ifdef IOI2021SG
    #define printl(args...)printf(args)
#else
    #define printl(args...)
#endif
#define mod 1000000007
vector<int>aux;
array<int,2>v[505];
ll dp[1005][505],inv[505];
int main(){
    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);
}

Compilation message (stderr)

boat.cpp: In function 'void usaco(std::string)':
boat.cpp:5:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    5 | void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
boat.cpp:5:66: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    5 | void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
      |                                                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
boat.cpp: In function 'int main()':
boat.cpp:26:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   26 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
boat.cpp:32:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   32 |         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