138 lines
4.4 KiB
C++
138 lines
4.4 KiB
C++
#include<iostream>
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#include<cstring>
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#include<algorithm>
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#include<cassert>
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#include<cstdio>
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#define unlikely(x) __builtin_expect(!!(x), 0)
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struct char_reader
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{
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FILE* f; char *buf,*p1,*p2; int size;
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char_reader(FILE* fin,int bufsize=1<<16) { f=fin; size=bufsize; p1=p2=0; buf=new char[size]; }
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~char_reader() { delete []buf; }
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inline int operator()() { return p1==p2&&(p2=(p1=buf)+fread(buf,1,size,f),p1==p2)?EOF:*p1++; }
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};
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struct char_writer
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{
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FILE* f; char *buf,*p,*end; int size;
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char_writer(FILE* fout,int bufsize=1<<16) { f=fout; size=bufsize; buf=new char[size]; p=buf; end=buf+bufsize; }
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~char_writer() { fwrite(buf,p-buf,1,f); delete []buf; }
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inline char operator()(char ch)
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{
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if(unlikely(end==p)) { fwrite(buf,end-buf,1,f); p=buf; }
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return *p++=ch;
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}
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};
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char_reader gch(stdin);
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char_writer wch(stdout);
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template<typename T> inline int read(T& t)
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{
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bool f=false; int ch; while(ch=gch(),!((ch>='0'&&ch<='9')||ch=='-')) { if(ch==EOF) return 0; }
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t=0;
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if(ch=='-') f=true,ch=gch(); t=ch^48; while(ch=gch(),ch>='0'&&ch<='9') t=(t<<3)+(t<<1)+(ch^48);
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if(f) t=-t;
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return 1;
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}
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inline int read(char &c)
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{
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c=0; int ch; while(ch=gch(),(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')) { if(ch==EOF) return 0; } c=ch;
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return 1;
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}
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inline int read(char *s)
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{
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int ch; while(ch=gch(),(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')) { if(ch==EOF) return 0; }
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*s++=ch; while(ch=gch(),!(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')&&ch!=EOF) *s++=ch;
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return 1;
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} inline int read(const char *s) { return read((char*)s); }
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inline int readline(char *s)
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{
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int ch; while(ch=gch(),(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')) { if(ch==EOF) return 0; }
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*s++=ch; while(ch=gch(),!(ch=='\n'||ch=='\r')&&ch!=EOF) *s++=ch;
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return 1;
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} inline int readline(const char *s) { return readline((char*)s); }
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template<typename T> inline void write(T t)
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{
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int stk[20],cnt=0;
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if(t==0) { wch('0'); return; } if(t<0) { wch('-'); t=-t; }
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while(t>0) { stk[cnt++]=t%10; t/=10; } while(cnt) wch(stk[--cnt]+'0');
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}
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inline void write(char t) { wch(t); }
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inline void write(char *s) { while(*s) wch(*s++); } inline void write(const char *s) { write((char*)s); }
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#if __cplusplus >= 201103L
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template<typename T,typename... Args> inline int read(T& t,Args&... args) { return read(t)+read(args...); }
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template<typename T,typename... Args> inline void write(T t,Args... args) { write(t); write(args...); }
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#else
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template<typename A_t,typename B_t> inline int read(A_t &a,B_t &b) { return read(a)+read(b); }
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template<typename A_t,typename B_t,typename C_t> inline int read(A_t &a,B_t &b,C_t &c) { return read(a)+read(b)+read(c); }
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template<typename A_t,typename B_t,typename C_t,typename D_t> inline int read(A_t &a,B_t &b,C_t &c,D_t &d) { return read(a)+read(b)+read(c)+read(d); }
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template<typename A_t,typename B_t> inline void write(A_t a,B_t b) { write(a); write(b); }
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template<typename A_t,typename B_t,typename C_t> inline void write(A_t a,B_t b,C_t c) { write(a); write(b); write(c); }
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template<typename A_t,typename B_t,typename C_t,typename D_t> inline void write(A_t a,B_t b,C_t c,D_t d) { write(a); write(b); write(c); write(d); }
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#endif
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using namespace std;
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typedef long long LL;
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const LL mod=998244353;
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const int maxn=1e6+10;
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int N,M,type,r[maxn];
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LL cnt1[2005],cnt2[2005];
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LL Factor[maxn*2];
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#define Frac(n) (Factor[n])
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LL Ksm(LL a,LL b)
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{
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LL res=1,x=a;
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while(b)
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{
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if(b&1) res=(res*x)%mod;
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x=(x*x)%mod;
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b>>=1;
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}
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return res;
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}
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inline LL inv(LL n)
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{
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return Ksm(n,mod-2);
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}
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inline LL Combination(int n,int m)
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{
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return (Frac(n)*inv(Frac(m)*Frac(n-m)%mod))%mod;
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}
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int solve0()
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{
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int Blank=M;
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for(int i=1;i<=N;i++) Blank-=2*r[i]-1;
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if(Blank<0) return 0;
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return (Frac(Blank+N)*inv(Frac(Blank)))%mod;
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}
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int solve1()
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{
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assert(N>0);
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if(N==1) return M;
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LL res=0;
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int Blank=M;
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for(int i=1;i<=N;i++) Blank-=2*r[i]-1;
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for(int i=1;i<=N;i++) cnt1[r[i]]++;
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for(int i=2;i<=2000;i++)
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for(int j=1;j<=i-1;j++)
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cnt2[i]=(cnt2[i]+cnt1[j]*cnt1[i-j])%mod;
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for(int i=1;i<=1000;i++) cnt2[i*2]-=cnt1[i];
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// for(int i=1;i<=N;i++)
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// for(int j=1;j<=N;j++)
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// if(i!=j&&Blank+r[i]+r[j]-2>=0)
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// res=(res+Combination(Blank+N+r[i]+r[j]-2,N))%mod;
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for(int i=max(2,2-Blank);i<=2000;i++)
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res=(res+Combination(Blank+N+i-2,N)*cnt2[i])%mod;
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res=(res*Frac(N-2))%mod;
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return res;
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}
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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read(N,M,type);
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Factor[0]=1;
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for(int i=1;i<maxn*2;i++) Factor[i]=(Factor[i-1]*i)%mod;
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for(int i=1;i<=N;i++) read(r[i]);
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if(type==0) printf("%d\n",solve0());
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else printf("%d\n",solve1());
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return 0;
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} |