Submission #1224449

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Source Code Expand

#include<stdio.h>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<bitset>
#include<utility>
#include<functional>
#include<iomanip>
#include<sstream>
#include<ctime>
#include<cassert>
using namespace std;
#define y0 y0z
#define y1 y1z
#define yn ynz
#define j0 j0z
#define j1 j1z
#define jn jnz
#define tm tmz
#define buli(x) (__builtin_popcountll(x))
#define bur0(x) (__builtin_ctzll(x))
#define bul2(x) (63-__builtin_clzll(x))
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define fil(a,b) memset((a),(b),sizeof(a))
#define cl(a) fil(a,0)
#define siz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
#define foreach(it,a) for(__typeof((a).begin()) it=(a).begin();it!=(a).end();it++)
#define rep(i,a,b) for (int i=(a),_ed=(b);i<_ed;i++)
#define per(i,a,b) for (int i=(b)-1,_ed=(a);i>=_ed;i--)
#define forg(i,gu) for (int i=gu;~i;i=e[i].next)
#define pw(x) ((ll(1))<<(x))
#define upmo(a,b) (((a)=((a)+(b))%mo)<0?(a)+=mo:(a))
#define mmo(a,b) (((a)=1ll*(a)*(b)%mo)<0?(a)+=mo:(a))
void getre(){int x=0;printf("%d\n",1/x);}
void gettle(){int res=1;while(1)res<<=1;printf("%d\n",res);}
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;
template<typename T,typename S>inline bool upmin(T&a,const S&b){return a>b?a=b,1:0;}
template<typename T,typename S>inline bool upmax(T&a,const S&b){return a<b?a=b,1:0;}
template<typename N,typename PN>inline N flo(N a,PN b){return a>=0?a/b:-((-a-1)/b)-1;}
template<typename N,typename PN>inline N cei(N a,PN b){return a>0?(a-1)/b+1:-(-a/b);}
template<typename N>N gcd(N a,N b){return b?gcd(b,a%b):a;}
template<typename N>inline int sgn(N a){return a>0?1:(a<0?-1:0);}
#if ( ( _WIN32 || __WIN32__ ) && __cplusplus < 201103L)
#define lld "%I64d"
#else
#define lld "%lld"
#endif
inline void gn(long long&x){
	int sg=1;char c;while(((c=getchar())<'0'||c>'9')&&c!='-');c=='-'?(sg=-1,x=0):(x=c-'0');
	while((c=getchar())>='0'&&c<='9')x=x*10+c-'0';x*=sg;
}
inline void gn(int&x){long long t;gn(t);x=t;}
inline void gn(unsigned long long&x){long long t;gn(t);x=t;}
inline void gn(double&x){double t;scanf("%lf",&t);x=t;}
inline void gn(long double&x){double t;scanf("%lf",&t);x=t;}
inline void gs(char *s){scanf("%s",s);}
inline void gc(char &c){while((c=getchar())>126 || c<33);}
inline void pc(char c){putchar(c);}
#ifdef JCVB
#define debug(...) fprintf(stderr, __VA_ARGS__)
#else
#define debug(...)
#endif
typedef long long ll;
typedef double db;
inline ll sqr(ll a){return a*a;}
inline db sqrf(db a){return a*a;}
const int inf=0x3f3f3f3f;
//const ll inf=0x3f3f3f3f3f3f3f3fll;
const db pi=3.14159265358979323846264338327950288L;
const db eps=1e-6;
const int mo=1e9+7;
int qp(int a,ll b){int n=1;do{if(b&1)n=1ll*n*a%mo;a=1ll*a*a%mo;}while(b>>=1);return n;}


int n,m;
int b;

int f[3333][3333];
int totf[3333];
int g[3333][3333];
int totg[3333];
int main()
{
#ifdef JCVB
	//freopen("1.in","r",stdin);
	//freopen("1.out","w",stdout);
	int _time_jc=clock();
#endif
	gn(n);gn(m);
	b=n-1;
	int ret=qp(2,m+1);// no updown
	if(b==0){
		printf("%d\n",ret);
		return 0;
	}

	int ans=0;
	f[0][0]=1;
	rep(j,0,m+1)
		rep(k,0,j+1)if(f[j][k]){
			upmo(totf[j],f[j][k]);
			upmo(f[j+1][k],2ll*f[j][k]);
			if(k+1<=b)upmo(f[j+1][k+1],f[j][k]);
			if(k) upmo(f[j+1][k-1],f[j][k]);
		}
	g[0][0]=1;
	rep(j,0,m+1)
		rep(k,0,j+1)if(g[j][k]){
			upmo(totg[j],g[j][k]);
			upmo(g[j+1][k],2ll*g[j][k]);
			if(k+1<=b-1)upmo(g[j+1][k+1],g[j][k]);
			if(k) upmo(g[j+1][k-1],g[j][k]);
		}

	int tot=qp(4,m-1);
	int tmp=0;
	for (int l=2;l<=m-1;l++){
		for (int t=0;t+l<=m-1;t++){
			int re=m-1-t-l;
			re=qp(4,re);
			mmo(re,totf[t]);
			mmo(re,g[l-2][b-1]);
			upmo(tmp,re);
		}
	}
	mmo(tmp,2ll);
	upmo(tot,-tmp);
	mmo(tot,4);
	printf("%d\n",tot);
#ifdef JCVB
	debug("time: %d\n",int(clock()-_time_jc));
#endif
	return 0;
}

Submission Info

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