【NOI2011】阿狸的打字机

题面

https://www.luogu.org/problem/P2414

题解

// luogu-judger-enable-o2
#include<cstdio>
#include<iostream>
#include<cstring>
#include<queue>
#include<algorithm>
#include<vector>
#define ri register int
#define N 100500
using namespace std;
char s[N];
int m,poi[N],dfx[N],dfy[N],cc,tot;
vector<int> son[N];
struct node {
  int l,r,id;
} q[N];
vector<node> qq[N];

int ff[N],ch[N][26];
int sun[N][26];
int nex[N];
int ans[N],p;


struct tree{
  int tt[N];
  void insert(int x,int k) {
    for (ri i=x;i<=cc;i+=(i&(-i))) tt[i]+=k;
  }
  int query(int x,int y) {
    int sum1=0,sum2=0;
    for (ri i=x-1;i;i-=(i&(-i))) sum1+=tt[i];
    for (ri i=y;i;i-=(i&(-i))) sum2+=tt[i];
    return sum2-sum1;
  }
} t;

void dfs(int x){
  dfx[x]=++cc;
  for (ri i=0;i<son[x].size();i++) dfs(son[x][i]);
  dfy[x]=cc;
}

void build() {
  queue<int> q;
  for (ri i=0;i<26;i++) if(ch[0][i]) q.push(ch[0][i]);
  while (!q.empty()) {
    int x=q.front(); q.pop();
    for (ri i=0;i<26;i++) {
      int y=ch[x][i];
      if (!y) ch[x][i]=ch[nex[x]][i]; else nex[y]=ch[nex[x]][i],q.push(y);
    }
  }
}

void solve(int x){
  t.insert(dfx[x],1);
  for (ri i=0;i<qq[x].size();i++) {
    ans[qq[x][i].id]=t.query(dfx[poi[qq[x][i].l]],dfy[poi[qq[x][i].l]]);
  }
  for (ri i=0;i<26;i++) if (sun[x][i]) solve(sun[x][i]);
  t.insert(dfx[x],-1);
}

int n;
int main(){
  scanf("%s",s+1);
  int n=strlen(s+1);
  int cur=0,cnt=0;
  tot=0;
  for (ri i=1;i<=n;i++) {
    if (s[i]=='B') cur=ff[cur];
    else if (s[i]=='P') poi[++cnt]=cur;
    else if (s[i]>='a' && s[i]<='z') {
      int c=s[i]-'a';
      if (!ch[cur][c]) sun[cur][c]=ch[cur][c]=++tot,ff[tot]=cur;
      cur=ch[cur][c];
    }
  }
  build();
  for (ri i=1;i<=tot;i++) son[nex[i]].push_back(i);
  cc=0;
  dfs(0);
  scanf("%d",&m);
  for (ri i=1;i<=m;i++) {
    scanf("%d %d",&q[i].l,&q[i].r);
    q[i].id=i;
    qq[poi[q[i].r]].push_back(q[i]);
  }
  solve(0);
  for (ri i=1;i<=m;i++) printf("%d
",ans[i]);
}