提交时间:2025-01-07 19:25:51
运行 ID: 35875
#include<bits/stdc++.h> #define up(i,l,r) for(int i=(l);i<=(r);++i) #define down(i,l,r) for(int i=(l);i>=(r);--i) #define pi pair<int,int> #define p1 first #define p2 second #define m_p make_pair #define p_b push_back typedef long long ll; using namespace std; const int maxn=1e6+10,mod=998244353; inline ll read(){ ll x=0;short t=1;char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')t=-1;ch=getchar();} while(ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar(); return x*t; } int qp(int a,int b){ int res=1; while(b){ if(b&1)res=res*1ll*a%mod; a=a*1ll*a%mod;b>>=1; }return res; } const int G=3,Gi=(mod+1)/3; #define poly vector<int> int rev[1<<21],n; int trans(int x){ int res=0; down(i,n-1,0)res=(res<<1)+(x&1),x>>=1; return res; } int pw[1<<21]; int jc[maxn]; void NTT(poly &a,int op=1){ up(i,0,(1<<n)-1)rev[i]=trans(i); up(i,0,(1<<n)-1)if(i<rev[i])swap(a[i],a[rev[i]]); int x=op?G:Gi; int N=(1<<n); for(int k=1;k<N;k<<=1){ int v=qp(x,(mod-1)/k/2); pw[0]=1;up(i,1,k-1)pw[i]=pw[i-1]*1ll*v%mod; up(i,0,N-1)if(!(i&k)){ int p=pw[i&(k-1)]; int x=a[i],y=a[i+k]*1ll*p%mod; a[i+k]=(x-y+mod)%mod; a[i]=(x+y)%mod; } } if(!op){ int iv=qp(N,mod-2); for(int &x:a)x=x*1ll*iv%mod; } } poly operator*(poly a,poly b){ n=0;while((1<<n)<=(int)a.size()+(int)b.size()+5)n++; a.resize(1<<n),b.resize(1<<n); NTT(a,1);NTT(b,1); up(i,0,(1<<n)-1)a[i]=a[i]*1ll*b[i]%mod; NTT(a,0); while(a.size()&&(!a.back()))a.pop_back(); return a; } poly S; void get(int n){ jc[0]=1;up(i,1,n)jc[i]=jc[i-1]*1ll*i%mod; poly A(n+1),B(n+1); up(i,0,n)A[i]=qp(jc[i],mod-2)*1ll*((i&1)?(mod-1):1)%mod,B[i]=qp(i,n)*1ll*qp(jc[i],mod-2)%mod; S=A*B;S.resize(n+1); up(i,0,n)S[i]=S[i]*1ll*jc[i]%mod; } void solve_35pts(int n,int m,int x){ int M=1,res=0; up(i,1,x){ (res+=qp(x+1-i,n)*1ll*M%mod)%=mod; M=M*1ll*(m+i-1)%mod*1ll*qp(i,mod-2)%mod; } cout<<res; } const int 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int JC(int x){ int B=1e6; int res=T[x/B]; up(i,x/B*B+1,x)res=res*1ll*i%mod; return res; } void solve_55pts(int n,int m,int x){ get(n); //int res=1;up(i,x+1,x+m)res=res*1ll*i%mod; //up(i,1,m)res=res*1ll*qp(i,mod-2)%mod; int res=JC(x+m)*1ll*qp(JC(x),mod-2)%mod*1ll*qp(JC(m),mod-2)%mod; int ans=0; up(i,0,n){ //cout<<res<<" "<<S[i]<<endl; (ans+=res*1ll*S[i]%mod)%=mod; res=res*1ll*qp(i+1+m,mod-2)%mod*1ll*(x-i)%mod; }cout<<ans; } const int MAXN=2e7+10; #define jc jcc int w[MAXN],p[MAXN],s[MAXN],iv[MAXN]; int jc[MAXN],jc_inv[MAXN]; int get_C(int n,int m){if(n<0||m<0||m<n)return 0;return JC(m)*1ll*qp(JC(n),mod-2)%mod*1ll*qp(JC(m-n),mod-2)%mod;} void solve_15pts(int n,int m,int x){ int c=0;w[1]=1; up(i,2,2e7){ if(!w[i])w[i]=qp(i,n),p[++c]=i; up(j,1,c){ if(i*p[j]>2e7)break; w[i*p[j]]=w[i]*1ll*w[p[j]]%mod; if(!(i%p[j]))break; } } int need=min(n+m+5,x),M=JC(x-need+m-1)*1ll*qp(JC(m-1),mod-2)%mod*1ll*qp(JC(x-need),mod-2)%mod; down(i,need,1){ w[i]=w[i]*1ll*M%mod; M=M*1ll*(m+x-i)%mod*1ll*qp(x-i+1,mod-2)%mod; } jc[0]=1;up(i,1,need)jc[i]=jc[i-1]*1ll*i%mod; jc_inv[need]=qp(jc[need],mod-2);down(i,need,1)jc_inv[i-1]=jc_inv[i]*1ll*i%mod; jc[0]=1;up(i,1,need)jc[i]=jc[i-1]*1ll*(x-i)%mod; iv[need]=qp(jc[need],mod-2);down(i,need,1)iv[i-1]=iv[i]*1ll*(x-i)%mod; up(i,1,need)iv[i]=iv[i]*1ll*jc[i-1]%mod; up(i,1,need)(w[i]+=w[i-1])%=mod; if(x<=need){cout<<w[x];return;} int res=0,v=JC(x-1)*1ll*qp(JC(x-1-need),mod-2)%mod; up(i,1,need)(res+=w[i]*1ll*v%mod*1ll*jc_inv[i-1]%mod*1ll*jc_inv[need-i]%mod*1ll*iv[i]%mod*1ll*(((need-i)&1)?mod-1:1)%mod)%=mod; cout<<res; } #undef jc void slv(){ int n=read(),m=read(),x=read(); if(x<=1e7){ solve_35pts(n,m,x); return; } if(n<=1e6){ solve_55pts(n,m,x); return; } if(n+m<=2e7){ solve_15pts(n,m,x); return; } } int main(){ //freopen("old.in","r",stdin); //freopen("old.out","w",stdout); slv(); fclose(stdin); fclose(stdout); return 0; }