BZOJ3764 : Petya的序列

#include<cstdio>
#include<algorithm>
typedef unsigned long long ll;
const int N=2005,M=100010;
int n,m,p,lim,i,j,a[N],v[N],s[N],g[M],nxt[N],vis[M];
int b[N],c[N],cnt,pos[N],ex,L[N],R[N],q[N],t;
ll f[M],C[M][5],sum[N],ans;
inline void read(int&a){char c;while(!(((c=getchar())>=‘0‘)&&(c<=‘9‘)));a=c-‘0‘;while(((c=getchar())>=‘0‘)&&(c<=‘9‘))(a*=10)+=c-‘0‘;}
inline int trans(int x){
  if(x==0)return -1;
  int t=x;
  while(x){
    int y=x%10;
    if(y!=4&&y!=7)return -1;
    x/=10;
  }
  return t;
}
inline int lower(int x){
  int l=1,r=n,mid,t;
  while(l<=r)if(b[mid=(l+r)>>1]<=x)l=(t=mid)+1;else r=mid-1;
  return t;
}
inline int add(int x,int y){nxt[y]=g[x];g[x]=y;}
inline void del(int x){
  if(x<0)return;
  if(vis[x])return;
  vis[x]=1;
  for(int i=g[x];i;i=nxt[i])if(i>lim){
    b[i]=++cnt;
    c[cnt]=i;
    if(i<ex)ex=i;
  }
}
inline ll cal(int l,int x,int r){return f[s[x-1]-s[l-1]]+f[s[r]-s[x]]-f[s[r]-s[l-1]];}
int main(){
  read(n);
  for(i=1;i<=n;i++)f[i]=1ULL*i*(i+1)/2ULL;
  for(i=1;i<=n;i++){
    C[i][1]=i;
    if(i<=4)C[i][i]=1;
    for(j=2;j<=4&&j<i;j++)C[i][j]=C[i-1][j-1]+C[i-1][j];
  }
  while(n--){
    read(i);
    i=trans(i);
    if(~i||a[m]>=0)a[++m]=i;else a[m]--;
  }
  for(i=1;i<=m;i++){
    if(a[i]>0)b[++p]=a[i],v[i]=1;else v[i]=-a[i];
    s[i]=s[i-1]+v[i];
  }
  if(p>1)for(std::sort(b+1,b+p+1),n=0,i=1;i<=p;i++)if(b[i]!=b[i-1])b[++n]=b[i];
  for(i=1;i<=m;i++)if(a[i]>0)add(a[i]=lower(a[i]),i);
  for(lim=1;lim<=m;lim++){
    for(cnt=i=0;i<=n;i++)vis[i]=0;
    ex=m+1;
    for(i=lim+1;i<=m;i++)b[i]=N;
    for(i=lim;i;i--){
      del(a[i]);
      pos[i]=cnt;
      if(i<lim){
        ans+=(C[v[lim]][3]+C[v[lim]][2]*(s[ex-1]-s[lim]+1))*v[i];
      }else{
        ans+=C[v[i]][2]+C[v[i]][3]*2ULL+C[v[i]][4];
        ans+=(C[v[i]][2]+C[v[i]][3])*(s[ex-1]-s[lim]);
      }
    }
    for(b[q[t=0]=lim]=0,i=lim+1;i<=m;q[++t]=i++){
      while(b[q[t]]>=b[i])t--;
      L[i]=q[t]+1;
    }
    for(b[q[t=0]=m+1]=0,i=m;i>lim;q[++t]=i--){
      while(b[q[t]]>=b[i])t--;
      R[i]=q[t]-1;
    }
    sum[0]=f[s[m]-s[lim]];
    for(i=1;i<=cnt;i++)sum[i]=sum[i-1]+cal(L[c[i]],c[i],R[c[i]]);
    ans+=sum[pos[lim]]*f[v[lim]];
    for(i=lim-1;i;i--)ans+=sum[pos[i]]*v[i]*v[lim];
  }
  return printf("%llu",ans),0;
}