省选模版复习——后缀数组

来源：互联网发布：微信支付demo java 编辑：程序博客网时间：2024/06/04 18:21
bzoj3238 后缀数组水
#include <cstdio>#include <cstring>#include <algorithm> using namespace std;const int Maxn=500005;typedef long long LL;LL Ans;char S[Maxn];int H[Maxn],Rank[Maxn],q[Maxn],pre[Maxn],nxt[Maxn];int l,r,N,i,j,k;struct Suf_Arr{  int x,num;  bool operator <(const Suf_Arr &a)const    { return x<a.x; }} Sa[Maxn]; void calc_height(){  for (i=1,k=0;i<=N;H[Rank[i++]]=k)    for (k=max(k-1,0),j=Sa[Rank[i]-1].num;S[i+k]==S[j+k];k++);} void Suffix_Array(){  scanf("%s",S+1);  N=strlen(S+1);  for (i=1;i<=N;i++)    Sa[i].num=i,Sa[i].x=S[i],Rank[i]=1;  for (int E=1;E<=N*2;E<<=1){    for (i=1,j=2;j<=N+1;j++)    if (Rank[Sa[j].num]!=Rank[Sa[i].num]){      sort(Sa+i,Sa+j);      Rank[Sa[i].num]=Rank[Sa[i-1].num]+1;      for (k=i+1;k<j;k++)      if (Sa[k].x==Sa[k-1].x) Rank[Sa[k].num]=Rank[Sa[k-1].num];        else Rank[Sa[k].num]=Rank[Sa[k-1].num]+1;      i = j;    }         for (i=1;i<=N;i++)    if (Sa[i].num+E>N) Sa[i].x=0;      else Sa[i].x=Rank[Sa[i].num+E];  }  calc_height();} void calc(){  H[0] = -1; H[N+1] = -1;  q[l=r=1]=0;  for (i=1;i<=N;i++){    while (l<=r && H[q[r]]>H[i]) r--;    pre[i] = q[r]; q[++r] = i;  }  q[l=r=1]=N+1;  for (i=N;i>0;i--){    while (l<=r && H[q[r]]>H[i]) r--;    nxt[i] = q[r]; q[++r] = i;  }     for (i=1;i<=N;i++){    Ans = Ans + (LL)(i-pre[i])*(nxt[i]-i)*H[i];    if (H[i]==H[nxt[i]]) pre[nxt[i]] = pre[i];  }  Ans = (LL)N*(N+1)/2*(N-1) - 2*Ans;  printf("%lld\n",Ans);} int main(){  //freopen("3238.in","r",stdin);  //freopen("3238.out","w",stdout);  Suffix_Array();  calc();  return 0;}
0 0