bzoj 1014 LCP 二分 Hash 匹配

求同一字符串的两个后缀的最长公共前缀。

将字符串按位置放到Splay中维护（每个节点还维护一下该子树的hash），然后二分前缀的长度，用splay计算出指定范围的hash，按hash是否相等来判断是否相同。

 /**************************************************************
     Problem: 1014
     User: idy002
     Language: C++
     Result: Accepted
     Time:7188 ms
     Memory:4900 kb
 ****************************************************************/

 #include <cstdio>
 #include <iostream>
 #include <cstring>
 #define maxn 100030
 using namespace std;

 typedef unsigned long long ulng;

 struct Splay {
     int pre[maxn], son[maxn][], ch[maxn], siz[maxn], ntot, root;
     ulng hash[maxn];
     ulng power[maxn];

     int newnode( int p, int c ) {
         int nd = ++ntot;
         pre[nd] = p;
         son[nd][] = son[nd][] = ;
         ch[nd] = c;
         siz[nd] = ;
         hash[nd] = c;
         return nd;
     }
     void update( int nd ) {
         int ls = son[nd][], rs = son[nd][];
         siz[nd] = siz[ls]+siz[rs]+;
         hash[nd] = hash[ls]*power[siz[rs]+]+ch[nd]*power[siz[rs]]+hash[rs];
     }
     int build( int p, const char *str, int lf, int rg ) {   //  [lf,rg]
         if( lf>rg ) return ;
         if( lf==rg ) return newnode(p,str[lf]-'a');
         int mid = (lf+rg)>>;
         int nd = newnode( p, str[mid]-'a' );
         son[nd][] = build( nd, str, lf, mid- );
         son[nd][] = build( nd, str, mid+, rg );
         update( nd );
         return nd;
     }
     void init( const char *str ) {
         root = ntot = ;
         power[] = 1ULL;
         for( int i=; i<maxn; i++ )
             power[i] = power[i-]*27ULL;

         root = newnode( , 'a'-'a' );
         int rnd = son[root][] = newnode( root, 'a'-'a' );
         son[rnd][] = build( rnd, str, , strlen(str)- );
         update( rnd );
         update( root );
     }
     void rotate( int nd, int d ) {
         int p = pre[nd];
         int s = son[nd][!d];
         int ss = son[s][d];

         son[nd][!d] = ss;
         son[s][d] = nd;
         if( p ) son[p][ nd==son[p][] ] = s;
         else root = s;

         pre[s] = p;
         pre[nd] = s;
         if( ss ) pre[ss] = nd;

         update( nd );
         update( s );
     }
     void splay( int nd, int top= ) {
         while( pre[nd]!=top ) {
             int p = pre[nd];
             int nl = nd==son[p][];
             if( pre[p]==top ) {
                 rotate( p, nl );
             } else {
                 int pp = pre[p];
                 int pl = p==son[pp][];
                 if( nl==pl ) {
                     rotate( pp, pl );
                     rotate( p, nl );
                 } else {
                     rotate( p, nl );
                     rotate( pp, pl );
                 }
             }
         }
     }
     int find( int pos ) {
         int nd = root;
         while() {
             int ls = siz[son[nd][]];
             if( nd== ) while();

             if( pos<=ls ) {
                 nd = son[nd][];
             } else if( pos>=ls+ ) {
                 nd = son[nd][];
                 pos -= ls+;
             } else return nd;
         }
     }
     void add_ch( int pos, int c ) {
         int lnd = find(pos);
         int rnd = find(pos+);
         splay(lnd);
         splay(rnd,lnd);
         son[rnd][] = newnode( rnd, c );
         splay( son[rnd][] );
     }
     void chg_ch( int pos, int c ) {
         int nd = find(pos);
         ch[nd] = c;
         update( nd );
         splay( nd );
     }
     ulng qu_hash( int lf, int rg ) {
         int lnd = find(lf-);
         int rnd = find(rg+);
         splay( lnd );
         splay( rnd, lnd );
         return hash[son[rnd][]];
     }
     inline int size() { return siz[root]-; }
 };

 Splay T;
 char str[maxn];
 int m;

 int main() {
     scanf( "%s", str );
     T.init(str);
     scanf( "%d", &m );
     while(m--) {
         char ch[];
         int pos, sa, sb;
         scanf( "%s", ch );
         if( ch[]=='I' ) {
             scanf( "%d%s", &pos, ch );
             pos++;
             T.add_ch( pos, ch[]-'a' );
         } else if( ch[]=='R' ) {
             scanf( "%d%s", &pos, ch );
             pos++;
             T.chg_ch( pos, ch[]-'a' );
         } else {
             scanf( "%d%d", &sa, &sb );
             sa++, sb++;
             if( T.qu_hash(sa,sa) != T.qu_hash(sb,sb) ) {
                 printf( "0\n" );
                 continue;
             }
             int len = T.size() - max(sa-,sb-) + ;
             int rl = , rr = len;
             while( rl<rr ) {
                 int md = (rl+rr+)>>;
                 ulng ha = T.qu_hash( sa, sa+md- );
                 ulng hb = T.qu_hash( sb, sb+md- );
                 if( ha==hb ) rl = md;
                 else rr = md-;
             }
             printf( "%d\n", rl );
         }
     }
 }