BZOJ4531 && BJOI2014 trace 

  1 #include<cstdio>
  2 #include<cctype>
  3 using namespace std ; 
  4 
  5 struct state {
  6     int len ;
  7     int p ; 
  8     int h ; 
  9     int last ; 
 10     state ( const int len , const int p , const int h , 
 11             const int last ) : len ( len ) , p ( p ) , h ( h ) , 
 12             last ( last ) {} ;
 13     int hash () const {
 14         return len * 6000 + 250 * p + h * 7 + last ;
 15         //this is a perfect hash 
 16     }
 17 } ;
 18 
 19 const int MAXN = 25 ; 
 20 const long long MOD = ( long long ) ( 1e9 + 7 ) ;
 21 int N , M , K ;
 22 
 23 int G [ MAXN ] [ MAXN ] ; 
 24 char s [ MAXN ] ; 
 25 
 26 const int size_of_dp = 2000000 ;
 27 long long dp [ size_of_dp ] ;
 28 bool vis [ size_of_dp ] ;
 29 
 30 int main () ; //complete checking checked
 31 long long D ( const state o ) ; //complete
 32 long long T ( const state o , const int p ) ;//complete
 33 long long T0 ( const state o , const int p ) ;//complete
 34 long long T1 ( const state o , const int p ) ;//complete 
 35 long long T2 ( const state o , const int p ) ;//complete 
 36 long long T3 ( const state o , const int p ) ;//complete 
 37 long long T4 ( const state o , const int p ) ;//complete
 38 long long T5 ( const state o , const int p ) ;//complete
 39 
 40 long long D ( const state o ) {
 41     if ( vis [ o . hash () ] ) return dp [ o . hash () ] ;
 42     vis [ o . hash () ] = true ; 
 43     if ( o . len == K ) {
 44         if ( o . h == 0 && o . last < 3 ) 
 45             return dp [ o . hash () ] = 1 ; 
 46         else return 0 ;
 47     }
 48     long long ans = 0 ; 
 49     for ( int i = 1 ; i <= N ; ++ i ) 
 50     if ( G [ o . p ] [ i ] ) {
 51         ans += T ( o , i ) ;
 52         ans %= MOD ;
 53     }
 54     #ifdef DEBUG
 55     printf ( "(%d,%d,%d,%d)=%lld\n" , o . len , o . p , o . h , o . last , ans ) ;
 56     #endif
 57     return dp [ o . hash () ] = ans ;     
 58 }
 59 
 60 long long T ( const state o , const int p ) {
 61     switch ( o . last ) {
 62         case 0 : return T0 ( o , p ) ; 
 63         case 1 : return T1 ( o , p ) ;
 64         case 2 : return T2 ( o , p ) ; 
 65         case 3 : return T3 ( o , p ) ; 
 66         case 4 : return T4 ( o , p ) ; 
 67         case 5 : return T5 ( o , p ) ; 
 68     }
 69     return 233 ;
 70 }
 71 
 72 int main () {
 73     freopen ( "trace.in" , "r" , stdin ) ; 
 74     freopen ( "trace.out" , "w" , stdout ) ; 
 75     scanf ( "%d%d%d" , & N , & M , & K ) ; 
 76     scanf ( "%s" , s + 1 ) ; 
 77     while ( M -- ) {
 78         int a , b ;
 79         scanf ( "%d%d" , & a , & b ) ; 
 80         G [ a ] [ b ] = G [ b ] [ a ] = 1 ; 
 81     }
 82     for ( int i = 1 ; i <= N ; ++ i ) G [ 0 ] [ i ] = 1 ; 
 83     printf ( "%lld\n" , D ( state ( 0 , 0 , 0 , 3 ) ) ) ;
 84     return 0 ;
 85 }
 86 
 87 long long T0 ( const state o , const int p ) {
 88     if ( s [ p ] == ')' && o . h > 0 ) 
 89         return D ( state ( o . len + 1 , p , o . h - 1 , 2 ) ) ;
 90     if ( s [ p ] == '+' || s [ p ] == '-' || 
 91          s [ p ] == '*' || s [ p ] == '/' ) 
 92         return D ( state ( o . len + 1 , p , o . h , 5 ) ) ;
 93     return 0 ;
 94 }
 95 
 96 long long T1 ( const state o , const int p ) {
 97     if ( isdigit ( s [ p ] ) )
 98         return D ( state ( o . len + 1 , p , o . h , 1 ) ) ;
 99     if ( s [ p ] == '+' || s [ p ] == '-' ||
100          s [ p ] == '*' || s [ p ] == '/' ) 
101         return D ( state ( o . len + 1 , p , o . h , 5 ) ) ; 
102     if ( s [ p ] == ')' && o . h > 0 ) 
103         return D ( state ( o . len + 1 , p , o . h - 1 , 2 ) ) ;
104     return 0 ;
105 }
106 
107 long long T2 ( const state o , const int p ) {
108     if ( s [ p ] == '+' || s [ p ] == '-' ||
109          s [ p ] == '*' || s [ p ] == '/' ) 
110         return D ( state ( o . len + 1 , p , o . h , 5 ) ) ; 
111     if ( s [ p ] == ')' && o . h > 0 ) 
112         return D ( state ( o . len + 1 , p , o . h - 1 , 2 ) ) ;
113     return 0 ; 
114 }
115 
116 long long T3 ( const state o , const int p ) {
117     if ( s [ p ] == '(' ) 
118         return D ( state ( o . len + 1 , p , o . h + 1 , 3 ) ) ;
119     if ( s [ p ] == '-' ) 
120         return D ( state ( o . len + 1 , p , o . h , 4 ) ) ;
121     if ( s [ p ] == '0' ) 
122         return D ( state ( o . len + 1 , p , o . h , 0 ) ) ; 
123     if ( s [ p ] >= '1' && s [ p ] <= '9' ) 
124         return D ( state ( o . len + 1 , p , o . h , 1 ) ) ; 
125     return 0 ;
126 }
127 
128 long long T4 ( const state o , const int p ) {
129     if ( s [ p ] == '0' ) 
130         return D ( state ( o . len + 1 , p , o . h , 0 ) ) ;
131     if ( s [ p ] >= '1' && s [ p ] <= '9' ) 
132         return D ( state ( o . len + 1 , p , o . h , 1 ) ) ; 
133     if ( s [ p ] == '(' ) 
134         return D ( state ( o . len + 1 , p , o . h + 1 , 3 ) ) ;
135     return 0 ; 
136 }
137 
138 long long T5 ( const state o , const int p ) {
139     if ( s [ p ] == '0' ) 
140         return D ( state ( o . len + 1 , p , o . h , 0 ) ) ;
141     if ( s [ p ] >= '1' && s [ p ] <= '9' ) 
142         return D ( state ( o . len + 1 , p , o . h , 1 ) ) ; 
143     if ( s [ p ] == '(' ) 
144         return D ( state ( o . len + 1 , p , o . h + 1 , 3 ) ) ;
145     return 0 ; 
146 }

 

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。。

 

posted @ 2016-03-18 15:33  Chris_2  阅读(177)  评论(0)  编辑  收藏  举报