BZOJ4531 && BJOI2014 trace

 #include<cstdio>
 #include<cctype>
 using namespace std ; 

 struct state {
     int len ;
     int p ;
     int h ;
     int last ;
     state ( const int len , const int p , const int h ,
             const int last ) : len ( len ) , p ( p ) , h ( h ) ,
             last ( last ) {} ;
     int hash () const {
         return len *  +  * p + h *  + last ;
         //this is a perfect hash
     }
 } ;

 const int MAXN =  ;
 const long long MOD = ( long long ) ( 1e9 +  ) ;
 int N , M , K ;

 int G [ MAXN ] [ MAXN ] ;
 char s [ MAXN ] ; 

 const int size_of_dp =  ;
 long long dp [ size_of_dp ] ;
 bool vis [ size_of_dp ] ;

 int main () ; //complete checking checked
 long long D ( const state o ) ; //complete
 long long T ( const state o , const int p ) ;//complete
 long long T0 ( const state o , const int p ) ;//complete
 long long T1 ( const state o , const int p ) ;//complete
 long long T2 ( const state o , const int p ) ;//complete
 long long T3 ( const state o , const int p ) ;//complete
 long long T4 ( const state o , const int p ) ;//complete
 long long T5 ( const state o , const int p ) ;//complete

 long long D ( const state o ) {
     if ( vis [ o . hash () ] ) return dp [ o . hash () ] ;
     vis [ o . hash () ] = true ;
     if ( o . len == K ) {
         if ( o . h ==  && o . last <  )
             return dp [ o . hash () ] =  ;
         else return  ;
     }
     long long ans =  ;
     for ( int i =  ; i <= N ; ++ i )
     if ( G [ o . p ] [ i ] ) {
         ans += T ( o , i ) ;
         ans %= MOD ;
     }
     #ifdef DEBUG
     printf ( "(%d,%d,%d,%d)=%lld\n" , o . len , o . p , o . h , o . last , ans ) ;
     #endif
     return dp [ o . hash () ] = ans ;
 }

 long long T ( const state o , const int p ) {
     switch ( o . last ) {
         case  : return T0 ( o , p ) ;
         case  : return T1 ( o , p ) ;
         case  : return T2 ( o , p ) ;
         case  : return T3 ( o , p ) ;
         case  : return T4 ( o , p ) ;
         case  : return T5 ( o , p ) ;
     }
     return  ;
 }

 int main () {
     freopen ( "trace.in" , "r" , stdin ) ;
     freopen ( "trace.out" , "w" , stdout ) ;
     scanf ( "%d%d%d" , & N , & M , & K ) ;
     scanf ( "%s" , s +  ) ;
     while ( M -- ) {
         int a , b ;
         scanf ( "%d%d" , & a , & b ) ;
         G [ a ] [ b ] = G [ b ] [ a ] =  ;
     }
     for ( int i =  ; i <= N ; ++ i ) G [  ] [ i ] =  ;
     printf ( "%lld\n" , D ( state (  ,  ,  ,  ) ) ) ;
     return  ;
 }

 long long T0 ( const state o , const int p ) {
     if ( s [ p ] == ')' && o . h >  )
         return D ( state ( o . len +  , p , o . h -  ,  ) ) ;
     if ( s [ p ] == '+' || s [ p ] == '-' ||
          s [ p ] == '*' || s [ p ] == '/' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     return  ;
 }

 long long T1 ( const state o , const int p ) {
     if ( isdigit ( s [ p ] ) )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] == '+' || s [ p ] == '-' ||
          s [ p ] == '*' || s [ p ] == '/' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] == ')' && o . h >  )
         return D ( state ( o . len +  , p , o . h -  ,  ) ) ;
     return  ;
 }

 long long T2 ( const state o , const int p ) {
     if ( s [ p ] == '+' || s [ p ] == '-' ||
          s [ p ] == '*' || s [ p ] == '/' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] == ')' && o . h >  )
         return D ( state ( o . len +  , p , o . h -  ,  ) ) ;
     return  ;
 }

 long long T3 ( const state o , const int p ) {
     if ( s [ p ] == '(' )
         return D ( state ( o . len +  , p , o . h +  ,  ) ) ;
     if ( s [ p ] == '-' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] == '' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] >= '' && s [ p ] <= '' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     return  ;
 }

 long long T4 ( const state o , const int p ) {
     if ( s [ p ] == '' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] >= '' && s [ p ] <= '' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] == '(' )
         return D ( state ( o . len +  , p , o . h +  ,  ) ) ;
     return  ;
 }

 long long T5 ( const state o , const int p ) {
     if ( s [ p ] == '' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] >= '' && s [ p ] <= '' )
         return D ( state ( o . len +  , p , o . h ,  ) ) ;
     if ( s [ p ] == '(' )
         return D ( state ( o . len +  , p , o . h +  ,  ) ) ;
     return  ;
 }

今天Z老把BJOI的题当练习给我们做，结果这道题只有50分。检查出来多写了一个+1，一脸。。