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 ;
}