菜死了被吊打成狗
T1：
多项式
板子
好像也可以分治
优化
#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define fi first
#define se second
#define bg begin
cs int RLEN=1<<20|1;
inline char gc(){
static char ibuf[RLEN],*ib,*ob;
(ib==ob)&&(ob=(ib=ibuf)+fread(ibuf,1,RLEN,stdin));
return (ib==ob)?EOF:*ib++;
}
inline int read(){
char ch=gc();
int res=0;bool f=1;
while(!isdigit(ch))f^=ch=='-',ch=gc();
while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
return f?res:-res;
}
template<class tp>inline void chemx(tp &a,tp b){a<b?a=b:0;}
template<class tp>inline void chemn(tp &a,tp b){a>b?a=b:0;}
cs int mod=998244353;
inline int add(int a,int b){return (a+=b)>=mod?(a-mod):a;}
inline int dec(int a,int b){a-=b;return a+(a>>31&mod);}
inline int mul(int a,int b){static ll r;r=1ll*a*b;return (r>=mod)?(r%mod):r;}
inline void Add(int &a,int b){(a+=b)>=mod?(a-=mod):0;}
inline void Dec(int &a,int b){a-=b,a+=a>>31&mod;}
inline void Mul(int &a,int b){static ll r;r=1ll*a*b;a=(r>=mod)?(r%mod):r;}
inline int ksm(int a,int b,int res=1){if(a==0&&b==0)return 0;for(;b;b>>=1,Mul(a,a))(b&1)&&(Mul(res,a),1);return res;}
inline int Inv(int x){return ksm(x,mod-2);}
inline int fix(int x){return (x<0)?x+mod:x;}
typedef vector<int> poly;
namespace Poly{
cs int G=3,C=19,M=(1<<19)|5;
int *w[C+1],rev[M],inv[M];
inline void init_w(){
for(int i=1;i<=C;i++)w[i]=new int[(1<<(i-1))|1];
w[C][0]=1;int wn=ksm(G,(mod-1)/(1<<C));
for(int i=1,l=(1<<(C-1));i<l;i++)w[C][i]=mul(w[C][i-1],wn);
for(int i=C-1;i;i--)
for(int j=0,l=(1<<(i-1));j<l;j++)w[i][j]=w[i+1][j<<1];
inv[0]=inv[1]=1;
for(int i=2;i<M;i++)inv[i]=mul(mod-mod/i,inv[mod%i]);
}
inline void init_rev(int lim){
for(int i=0;i<lim;i++)rev[i]=(rev[i>>1]>>1)|((i&1)*(lim>>1));
}
inline void ntt(int *f,int lim,int kd){
for(int i=0;i<lim;i++)if(i>rev[i])swap(f[i],f[rev[i]]);
for(int mid=1,l=1,a0,a1;mid<lim;mid<<=1,l++)
for(int i=0;i<lim;i+=mid<<1)
for(int j=0;j<mid;j++)
a0=f[i+j],a1=mul(f[i+j+mid],w[l][j]),f[i+j]=add(a0,a1),f[i+j+mid]=dec(a0,a1);
if(kd==-1){
reverse(f+1,f+lim);
for(int i=0,iv=Inv(lim);i<lim;i++)Mul(f[i],iv);
}
}
inline poly operator *(poly a,poly b){
int deg=a.size()+b.size()-1;
if(deg<=32){
poly c(deg,0);
for(int i=0;i<a.size();i++)
for(int j=0;j<b.size();j++)
Add(c[i+j],mul(a[i],b[j]));
return c;
}
int lim=1;
while(lim<deg)lim<<=1;
a.resize(lim),ntt(&a[0],lim,1);
b.resize(lim),ntt(&b[0],lim,1);
for(int i=0;i<lim;i++)Mul(a[i],b[i]);
ntt(&a[0],lim,-1),a.resize(deg);
return a;
}
inline poly Inv(poly a,int deg){
poly b(1,::Inv(a[0])),c;
for(int lim=4;lim<(deg<<2);lim<<=1){
init_rev(lim);
c.resize(lim>>1),b.resize(lim>>1);
for(int i=0;i<(lim>>1);i++)c[i]=(a.size()>i?a[i]:0);
c.resize(lim),ntt(&c[0],lim,1);
b.resize(lim),ntt(&b[0],lim,1);
for(int i=0;i<lim;i++)b[i]=mul(b[i],dec(2,mul(b[i],c[i])));
ntt(&b[0],lim,-1),b.resize(lim>>1);
}
b.resize(deg);return b;
}
inline poly deriv(poly a){
for(int i=0;i<(int)a.size()-1;i++)a[i]=mul(a[i+1],i+1);
a.pop_back();return a;
}
inline poly integ(poly a){
a.pb(0);
for(int i=a.size()-1;i;i--)a[i]=mul(a[i-1],inv[i]);
a[0]=0;return a;
}
inline poly Ln(poly a,int deg){
a=integ(deriv(a)*Inv(a,deg)),a.resize(deg);return a;
}
inline poly Exp(poly a,int deg){
poly b(1,1),c;
for(int lim=2;lim<(deg<<1);lim<<=1){
c=Ln(b,lim);
for(int i=0;i<lim;i++)c[i]=dec(a.size()>i?a[i]:0,c[i]);
Add(c[0],1),b=b*c,b.resize(lim);
}
b.resize(deg);return b;
}
}
using Poly::init_w;
using Poly::Exp;
cs int N=100005;
int n,a;
int fac[N],ifac[N];
inline void init_inv(){
fac[0]=ifac[0]=1;
for(int i=1;i<N;i++)fac[i]=mul(fac[i-1],i);
ifac[N-1]=Inv(fac[N-1]);
for(int i=N-2;i;i--)ifac[i]=mul(ifac[i+1],i+1);
}
int main(){
init_w(),init_inv();
n=read(),a=read();
poly f;
f.resize(a+1);
f[1]=1;
for(int i=2;i<=a;i++)f[i]=mul(ksm(i,i-2),ifac[i]);
f=Exp(f,n+1);
cout<<mul(f[n],fac[n]);
return 0;
}
T2：
考虑实际上是满足两个位置
建出 启发式合并 用树状数组统计答案即可
#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define fi first
#define se second
#define bg begin
cs int RLEN=1<<20|1;
inline char gc(){
static char ibuf[RLEN],*ib,*ob;
(ib==ob)&&(ob=(ib=ibuf)+fread(ibuf,1,RLEN,stdin));
return (ib==ob)?EOF:*ib++;
}
inline int read(){
char ch=gc();
int res=0;bool f=1;
while(!isdigit(ch))f^=ch=='-',ch=gc();
while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
return f?res:-res;
}
inline int readstring(char *s){
int top=0;char ch=gc();
while(isspace(ch))ch=gc();
while(!isspace(ch)&&ch!=EOF)s[++top]=ch,ch=gc();
return top;
}
template<class tp>inline void chemx(tp &a,tp b){a<b?a=b:0;}
template<class tp>inline void chemn(tp &a,tp b){a>b?a=b:0;}
cs int N=300005;
int n,K;
struct Bit{
int tr[N],stk[N],top;
#define lb(x) (x&(-x))
inline void update(int p,int k){
stk[++top]=p;
for(;p<=n;p+=lb(p))tr[p]+=k;
}
inline int qry(int p,int res=0){
for(;p;p-=lb(p))res+=tr[p];return res;
}
inline void clear(){
while(top){
int p=stk[top--];
for(;p<=n;p+=lb(p))tr[p]=0;
}
}
int query(int l,int r){
l=max(1,l),r=min(n,r);
return qry(r)-qry(l-1);
}
#undef lb
}T;
namespace Sam{
cs int N=::N<<1;
int fa[N],nxt[N][26],len[N],ps[N],pos[N];
int last=1,tot=1;
inline void insert(int c,int id){
int cur=++tot,p=last;ps[id]=cur;pos[cur]=id;
last=cur,len[cur]=len[p]+1;
for(;p&&!nxt[p][c];p=fa[p])nxt[p][c]=cur;
if(!p)fa[cur]=1;
else{
int q=nxt[p][c];
if(len[p]+1==len[q])fa[cur]=q;
else{
int clo=++tot;
len[clo]=len[p]+1,fa[clo]=fa[q];
memcpy(nxt[clo],nxt[q],sizeof(nxt[q]));
for(;p&&nxt[p][c]==q;p=fa[p])nxt[p][c]=clo;
fa[cur]=fa[q]=clo;
}
}
}
vector<int> e[N],q[N];
int siz[N],son[N],top[N],dn[N];
void dfs1(int u){
siz[u]=1;
for(int &v:e[u]){
dfs1(v),siz[u]+=siz[v];
if(siz[v]>siz[son[u]])son[u]=v;
}
}
void dfs2(int u,int tp){
top[u]=tp,dn[tp]=u;
if(son[u])dfs2(son[u],tp);
for(int &v:e[u])if(v!=son[u]){
dfs2(v,v);
}
}
inline void build(){
for(int i=2;i<=tot;i++)e[fa[i]].pb(i);
dfs1(1),dfs2(1,1);
for(int i=1;i<=n;i++){
int u=ps[i];
while(u){
q[top[u]].pb(i);
u=fa[top[u]];
}
}
}
inline void solve(){
ll ans=0;
for(int i=1;i<=tot;i++)if(i==dn[top[i]]){
int u=i;T.clear();
while(0721){
int tp=len[u]/(K-1);
for(int &v:e[u])if(v!=son[u]){
for(int &x:q[v])
ans+=T.query(x-tp,x+tp);
for(int &x:q[v])
T.update(x,1);
}
if(pos[u])ans+=T.query(pos[u]-tp,pos[u]+tp),T.update(pos[u],1);
if(u==top[u])break;
u=fa[u];
}
}
cout<<ans<<'\n';
}
}
char s[N];
int main(){
#ifdef Stargazer
freopen("lx.in","r",stdin);
//freopen("my.out","w",stdout);
#endif
n=read(),K=read();
readstring(s);
for(int i=1;i<=n;i++)Sam::insert(s[i]-'a',i);
Sam::build();
Sam::solve();
return 0;
}
T3：
暴力即可
#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define fi first
#define se second
#define bg begin
cs int RLEN=1<<20|1;
inline char gc(){
static char ibuf[RLEN],*ib,*ob;
(ib==ob)&&(ob=(ib=ibuf)+fread(ibuf,1,RLEN,stdin));
return (ib==ob)?EOF:*ib++;
}
inline int read(){
char ch=gc();
int res=0;bool f=1;
while(!isdigit(ch))f^=ch=='-',ch=gc();
while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
return f?res:-res;
}
template<class tp>inline void chemx(tp &a,tp b){a<b?a=b:0;}
template<class tp>inline void chemn(tp &a,tp b){a>b?a=b:0;}
cs int N=3005;
pii p[N];
map<pii,int>vt;
int n;
inline bool operator ==(cs pii &a,cs pii &b){
return a.fi==b.fi&&a.se==b.se;
}
int main(){
n=read();
for(int i=1;i<=n;i++){
p[i].fi=read(),p[i].se=read();
vt[p[i]]++;
}
ll ans=0;
for(int i=1;i<=n;i++)
for(int j=i+1;j<=n;j++)if(p[i]!=p[j]){
ll dx=p[j].fi-p[i].fi,dy=p[j].se-p[i].se;
ll tx=p[i].fi+p[j].fi+dy,ty=p[i].se+p[j].se-dx;
if(!(tx&1)&&!(ty&1)){
tx/=2,ty/=2;
if(vt.count(pii(tx,ty)))ans+=vt[pii(tx,ty)];
}
tx=p[i].fi+p[j].fi-dy,ty=p[i].se+p[j].se+dx;
if(!(tx&1)&&!(ty&1)){
tx/=2,ty/=2;
if(vt.count(pii(tx,ty)))ans+=vt[pii(tx,ty)];
}
}
cout<<ans<<'\n';
return 0;
}
