pku2758 Checking the Text

 

题意：对原字符串插入若干字符后，动态查询某两个位置的lcp

RMQ用Square Table作O(nlogn)的预处理和O(1)的询问

#include <iostream>
#include <algorithm>
using namespace std;

#define MAXN 50010
#define Min(a,b) (a<b?a:b)

struct Ic{
    int pos;
    char ch;
}ic[210];

int b[MAXN],array[4][MAXN],*sa,*nsa,*rank,*nrank,height[MAXN],n,m,M[MAXN][20],icnt;
char str[MAXN];

void make_sa(){
    int i,k;

    sa=array[0];
    nsa=array[1];
    rank=array[2];
    nrank=array[3];

    memset(b,0,sizeof(b));
    for(i=0;i<n;i++)
        b[str[i]]++;
    for(i=1;i<=256;i++)
        b[i]+=b[i-1];
    for(i=n-1;i>=0;i--)
        sa[--b[str[i]]]=i;

    for(rank[sa[0]]=0,i=1;i<n;i++){
        rank[sa[i]]=rank[sa[i-1]];
        if(str[sa[i]]!=str[sa[i-1]])
            rank[sa[i]]++;
    }

    for(k=1;k<n && rank[sa[n-1]]<n-1;k*=2){
        for(i=0;i<n;i++)
            b[rank[sa[i]]]=i;
        for(i=n-1;i>=0;i--)
            if(sa[i]-k>=0)
                nsa[b[rank[sa[i]-k]]--]=sa[i]-k;

        for(i=n-k;i<n;i++)
            nsa[b[rank[i]]--]=i;

        for(nrank[nsa[0]]=0,i=1;i<n;i++){
            nrank[nsa[i]]=nrank[nsa[i-1]];
            if(rank[nsa[i]]!=rank[nsa[i-1]] || rank[nsa[i]+k]!=rank[nsa[i-1]+k])
                nrank[nsa[i]]++;
        }

        int *t=sa;sa=nsa;nsa=t;
        t=rank;rank=nrank;nrank=t;
    }
}

void get_height(){
    int i,j,k;
    for(i=0,k=0;i<n;i++){
        if(rank[i]==0)
            height[rank[i]]=0;
        else{
            for(j=sa[rank[i]-1];str[i+k]==str[j+k];k++);
            height[rank[i]]=k;
            if(k>0)
                k--;
        }
    }
}

void rmq_prepro(){/////////////////////////////////////////
    int i,j;
    for(i=0;i<n;i++)
        M[i][0]=i;
    for(j=1;(1<<j)<=n;j++){
        for(i=0;i+(1<<j)-1<n;i++){
            if(height[M[i][j-1]]<height[M[i+(1<<(j-1))][j-1]])
                M[i][j]=M[i][j-1];
            else
                M[i][j]=M[i+(1<<(j-1))][j-1];
        }
    }
}

void insert(char ch,int pos){
    int i,j;
    for(i=0;i<icnt;i++)
        if(ic[i].pos>=pos)
            break;
        else
            pos--;
    for(j=icnt++;j>i;j--)
        ic[j]=ic[j-1];
    if(pos>n-1)
        pos=n-1;
    ic[i].ch=ch;
    ic[i].pos=pos;
}
            

int lcp(int a,int b){////////////////////////////////////
    int k,t;
    a=rank[a];
    b=rank[b];
    if(a>b)
        swap(a,b);
    a++;//*
    t=b-a+1;
    for(k=0;(1<<k)<=t;k++);k--;
    return Min(height[M[a][k]],height[M[b-(1<<k)+1][k]]);
}

int mxlen(int a,int b){
    int i,j,k,x,y,ret=0,t;
    for(x=0;ic[x].pos<=a;x++);
    for(y=0;ic[y].pos<=b;y++);
    if(a==b)
        return n-a+icnt-x-2;
    while(1){
        k=lcp(a,b);//////////////////////////////
        i=ic[x].pos-a;
        j=ic[y].pos-b;
        t=Min(k,Min(i,j));
        ret+=t;a+=t;b+=t;
        if(i==t || j==t){
            while(ic[x].pos==a && ic[y].pos==b){
                if(ic[x].ch==ic[y].ch){
                    x++;y++;ret++;
                }
                else
                    return ret;
            }
            while(ic[x].pos==a){
                if(ic[x].ch==str[b]){
                    x++;b++;ret++;
                }
                else
                    return ret;
            }
            while(ic[y].pos==b){
                if(ic[y].ch==str[a]){
                    y++;a++;ret++;
                }
                else
                    return ret;
            }
        }
        else
            return ret;
    }
    return ret;
}

    

    



int main(){
    int i,j,t;
    char order[3];
    while(scanf("%s",str)!=EOF){
        scanf("%d",&m);
        n=strlen(str);
        str[n++]='#';
        str[n]='\0';

        make_sa();/////////
        get_height();////////
        rmq_prepro();////////

        ic[0].ch='#';
        ic[0].pos=MAXN;
        icnt=1;

        while(m--){
            scanf("%s",order);
            if(order[0]=='I'){
                scanf("%s",order);
                scanf("%d",&t);
                t--;
                insert(order[0],t);
            }
            else{
                scanf("%d%d",&i,&j);
                i--;
                j--;
                if(i>j)
                    swap(i,j);
                printf("%d\n",mxlen(i,j));
            }
        }
    }
    return 0;
}