bzoj1726 第二短路

一道严格次短路题，WA了一下午回家才发现bellman_ford中的vis [ o ] = false 写成了 vis [ S ] = false.被自己脑残了一脸。。。。

 #include<climits>
 #include<cstdio>
 #include<algorithm>
 #include<queue>
 using namespace std ; 

 void min_equal ( int & a , const int b ) {
     if ( a > b ) a = b ;
 }

 const int MAXN =  +  ;
 const int MAXR =  +  ; 

 struct edge {
     int dis ;
     int p ;
     edge * next ;
 } ;

 edge * V [ MAXN ] ;
 edge E [ MAXR *  ] ; 

 void add_edge ( const int a , const int b , const int dis ) {
     static edge * t = E ;
     edge * x = t ++ , * y = t ++ ;
     x -> dis = y -> dis = dis ;
     x -> p = b ; y -> p = a ;
     x -> next = V [ a ] ; y -> next = V [ b ] ;
     V [ a ] = x ; V [ b ] = y ;
 }

 int N , R ;
 int dis1 [ MAXN ] ;
 int dis2 [ MAXN ] ; 

 void bellman_ford ( const int S , const int T , int dis [] ) {
     static int vis [ MAXN ] ;
     static const int INF = INT_MAX ;
     static queue < int > q ;
     fill ( dis , dis + N +  , INF ) ;
     fill ( vis , vis + N +  ,  ) ;
     dis [ S ] =  ;
     vis [ S ] = true ;
     q . push ( S ) ;
     while ( ! q . empty () ) {
         const int o = q . front () ;
         q . pop () ;
         vis [ o ] = false ;
         for ( edge * v = V [ o ] ; v !=  ; v = v -> next )
         if ( dis [ o ] + v -> dis < dis [ v -> p ] ) {
             dis [ v -> p ] = dis [ o ] + v -> dis ;
             if ( ! vis [ v -> p ] ) {
                 vis [ v -> p ] = true ;
                 q . push ( v -> p ) ;
             }
         }
     }
 }

 int main () {
     scanf ( "%d%d" , & N , & R ) ;
     while ( R -- ) {
         int a , b , c ;
         scanf ( "%d%d%d" , & a , & b , & c ) ;
         add_edge ( a , b , c ) ;
     }
     bellman_ford (  , N , dis1 ) ;
     bellman_ford ( N ,  , dis2 ) ;
     int ans = INT_MAX ;
     for ( int i =  ; i <= N ; ++ i )
         for ( edge * v = V [ i ] ; v !=  ; v = v -> next ) {
             const int a = dis1 [ i ] + v -> dis + dis2 [ v -> p ] ;
             if ( a != dis1 [ N ] ) min_equal ( ans , a ) ;
         }
     printf ( "%d\n" , ans ) ;
     return  ;
 }