Submission #421364

#	Time	Username	Problem	Language	Result	Execution time	Memory
421364		juggernaut	Tents (JOI18_tents)	C++17	100 / 100	498 ms	71136 KiB

tents

#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...)((void)0)
#endif
ll dp[3005][3005];
ll mod=1e9+7;
inline ll add(ll a,ll b){
    return (a+b)%mod;
}
inline ll mult(ll a,ll b){
    return (a*b)%mod;
}
ll go(int n,int m){
    if(n==1)return 4*m+m*(m-1)/2+1;
    if(m==1)return 4*n+n*(n-1)/2+1;
    if(n==0||m==0)return 1;
    if(n<0||m<0)return 0;
    ll &res=dp[n][m];
    if(~res)return res;
    res=0;
    res=add(res,go(n-1,m));
    res=add(res,mult(4*m,go(n-1,m-1)));
    res=add(res,mult(go(n-1,m-2),m*(m-1)/2));
    res=add(res,mult(go(n-2,m-1),m*(n-1)));
    return res;
}
int main(){
    memset(dp,-1,sizeof dp);
    int n,m;
    scanf("%d%d",&n,&m);
    if(n>m)swap(n,m);
    ll ans=go(n,m);
    if(ans==0)ans=mod-1;
    else ans--;
    printf("%lld",ans);
}

Compilation message (stderr)

tents.cpp: In function 'void usaco(std::string)':
tents.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);}
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tents.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);}
      |                                                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp: In function 'int main()':
tents.cpp:45:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |     scanf("%d%d",&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52