Floyd-warshall(经典DP, 能用于有向图)

Floyd-warshall(经典DP, 能用于有向图)

闻说还能用在负权,和有环图...继续研究

const   int  MAXN  =   101 ;
const   int  INF  =   1000000 ;
int  g[MAXN][MAXN];
int  d[MAXN][MAXN];
int  floyd( int  n)
{
     int   i, j, k;
     for  (i = 1 ; i <= n; i ++ )
         for  (j = 1 ; j <= n; j ++ )
            d[i][j]  =  g[i][j];
     for  (k = 1 ; k <= n; k ++ )
     {
         for  (i = 1 ; i <= n; i ++ )
             for  (j = 1 ; j <= n; j ++ )
             {
                 if  (d[i][k]  <  INF  &&  d[k][j]  <  INF
                 &&  d[i][k]  +  d[k][j]  <  d[i][j])
                    d[i][j]  =  d[i][k]  +  d[k][j];
            }
    }
     return   0 ;
}