Submission #421654

#	Time	Username	Problem	Language	Result	Execution time	Memory
421654		Kerim	Tents (JOI18_tents)	C++17	100 / 100	219 ms	35908 KiB

tents

#include "bits/stdc++.h"
#define MAXN 100009
#define INF 1000000007
#define mp(x,y) make_pair(x,y)
#define all(v) v.begin(),v.end()
#define pb(x) push_back(x)
#define wr cout<<"----------------"<<endl;
#define ppb() pop_back()
#define tr(ii,c) for(__typeof((c).begin()) ii=(c).begin();ii!=(c).end();ii++)
#define ff first
#define ss second
#define my_little_dodge 46
#define debug(x)  cerr<< #x <<" = "<< x<<endl;
using namespace std;
 
typedef long long ll;
typedef pair<int,int> PII;
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
const int N=3003;
int dp[N][N],c[N];
int mod(ll x){
	return (x%INF);
}
int rec(int row,int empty){
	if(!row)return 1;
	int &ret=dp[row][empty];
	if(~ret)return ret;
	ret=rec(row-1,empty);
	//E W N S
	ret=mod(ret+rec(row-1,empty-1)*4LL*empty);
	//EW
	if(empty>=2)
		ret=mod(ret+rec(row-1,empty-2)*1LL*c[empty]);
	//SN
	ret=mod(ret+rec(row-2,empty-1)*1LL*mod((row-1)*1LL*empty));
	return ret;
}
int main(){
    //~ freopen("file.in", "r", stdin);
    memset(dp,-1,sizeof dp);
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++)
		c[i]=(i*(i-1))/2;
	printf("%d\n",mod(rec(n,m)-1+INF));
	return 0;
}

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:43:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |     scanf("%d%d",&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~

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