最小费用流

  1 #include <iostream>
  2 #include <cstdlib>
  3 #include <cstring>
  4 #include <cstdio>
  5 #include <queue>
  6 const int inf = 1 << 30 , N = 200 + 11 ;
  7 using namespace std ;
  8 int head[N] , n , m , dis[N] , mark[N] , cnt , s , t , ans ;
  9 struct id
 10 {
 11     int nxt , to  , val , vol ;
 12 } e[80011] ;
 13 queue < int > Q ;
 14 
 15 
 16 inline void Init( )
 17 {
 18     freopen( "NSOOJ#10399.in" , "r" , stdin ) ;
 19     freopen( "NSOOJ#10399.out" , "w" , stdout )   ;
 20 }
 21 
 22 
 23 void add( int a , int b  , int c , int d  )
 24 {
 25     e[++cnt].nxt = head[a] , e[cnt].to = b ;
 26     e[cnt].val = c , e[cnt].vol = d ; head[a] = cnt ;
 27 }
 28 
 29 int read(  ) {
 30     char ch = getchar(  ) ; int ret = 0 , k = 1 ;
 31     while( ch < ‘0‘ || ch > ‘9‘ ) { if( ch == ‘-‘ ) k = -1 ; ch = getchar(  ) ; }
 32     while( ch >= ‘0‘ && ch <= ‘9‘ ) ret = ret * 10 + ch - ‘0‘ , ch = getchar(  ) ;
 33     return ret * k ;
 34 }
 35 
 36 
 37 void input( )
 38 {
 39     n = read( ) , m = read( ) ; cnt = -1 ; 
 40     s = 1  , t = n  ; int a, b , c , d ;
 41     memset( head , -1 , sizeof(head) ) ;
 42     int maxn = 0 ;
 43     for( int x = 1 ; x <= m ; x ++ )
 44     {
 45         a = read( ) , b = read( ) , c = read( ) , d = read( ) ;
 46         add( a , b , c , d ) ;
 47         add( b , a , 0 , 0-d ) ; 
 48     }
 49 
 50 }
 51 
 52 
 53 bool spfa(  )
 54 {
 55     memset( mark , 0  , sizeof( mark ) ) ;
 56     for( int i = 0 ; i <= t ; i++ ) dis[i] = inf ;
 57     dis[t] = 0 , mark[t] = 1 ; Q.push( t ) ;
 58     while( !Q.empty( ) )
 59     {
 60         int u = Q.front( ) ; Q.pop( ) ;
 61         for( int i = head[u] ;~i ; i = e[i].nxt )
 62         {
 63             int v = e[i].to ;
 64             if( e[i^1].val && dis[u] + e[i^1].vol < dis[v] )
 65             {
 66                 dis[v] = dis[u] + e[i^1].vol ;
 67                 if( !mark[v] )
 68                 {
 69                     mark[v] = 1 ;
 70                     Q.push( v ) ;
 71                 }
 72             }
 73         }
 74         mark[u] = 0 ;
 75     }
 76     return dis[s] != inf ;
 77 }
 78 
 79 
 80 int dfs( int u , int f )
 81 {
 82     mark[u] = 1 ;
 83     if( u == t ) return f ;
 84     int w , used = 0 ;
 85     for( int i = head[u] ; ~i ; i = e[i].nxt )
 86     {
 87         int v = e[i].to ;//cout<<u<<" "<<v<<endl; 
 88         if( dis[v] == dis[u] - e[i].vol && e[i].val > 0 && !mark[v] )
 89         {
 90             w = f - used ;
 91             w = dfs( v , min( w , e[i].val ) ) ;
 92             ans += w * e[i].vol ;
 93             e[i].val -= w , e[i^1].val += w  , used += w ;
 94             if( used == f ) return f;
 95         }
 96     }
 97     return used ;
 98 }
 99 
100 
101 void zkw(  )
102 {
103     int sum = 0 ;
104     while( spfa(  ) )
105     {
106         mark[t] = 1 ;
107         while( mark[t] )
108         {
109             memset( mark , 0 , sizeof(mark) ) ;
110             sum += dfs( 1 , inf ) ;
111         }
112     }
113     printf( "%d %d\n" , sum , ans ) ;
114 }
115 
116 
117 
118 
119 int main (  )
120 {
121 //    Init( ) ;
122     input( ) ;
123     zkw( ) ;
124 //    fclose( stdin ) ;
125 //    fclose( stdout ) ;
126     return 0 ;
127 }