hdu1853 km算法

  1 //hdu1853 
  2 #include<stdio.h>
  3 #include<string.h>
  4 #define INF 99999999
  5 int map[103][103],pr[103],pl[103],visr[103],visl[103],slack[103],match[103];
  6 int n,m;
  7 int dfs(int u)
  8 {
  9     int i,j,val;
 10 
 11     visl[u]=1;
 12     for(i=1;i<=n;i++)
 13     {
 14         if(!visr[i])
 15         {
 16             val=pr[i]+pl[u]-map[u][i];
 17             if(val==0)
 18             {
 19                 visr[i]=1;
 20                 if(match[i]==-1||dfs(match[i]))
 21                 {
 22                     match[i]=u;
 23                     return 1;
 24                 }
 25             }
 26             if(val>0&&slack[i]>val)
 27                 slack[i]=val;
 28         }
 29     }
 30     return 0;
 31 }
 32 void km()
 33 {
 34     int i,j,res=0,d;
 35     for(i=0;i<=n;i++)
 36         pl[i]=INF;
 37     memset(pr,0,sizeof(pr));
 38     memset(match,-1,sizeof(match));
 39     for(i=1;i<=n;i++)
 40     {
 41         for(j=1;j<=n;j++)
 42             slack[j]=INF;
 43         while(1)
 44         {
 45             memset(visr,0,sizeof(visr));
 46             memset(visl,0,sizeof(visl));
 47             if(dfs(i))
 48                 break;
 49             d=INF;
 50             for(j=1;j<=n;j++)
 51             {
 52                 if(!visr[j]&&d>slack[j])
 53                     d=slack[j];
 54             }
 55             for(j=1;j<=n;j++)
 56             {
 57                 if(visr[j])
 58                     pr[j]+=d;
 59                 if(visl[j])
 60                     pl[j]-=d;
 61             }
 62         }
 63     }
 64 }
 65 int main()
 66 {
 67     int i,j;
 68     while(scanf("%d%d",&n,&m)!=EOF)
 69     {
 70         for(i=0;i<=n;i++)
 71             for(j=0;j<=n;j++)
 72                 map[i][j]=-INF;
 73 
 74         for(i=0;i<m;i++)
 75         {
 76             int x,y,z;
 77             scanf("%d%d%d",&x,&y,&z);
 78             if(map[x][y]<-z)
 79             {
 80                 map[x][y]=-z;
 81             }
 82         }
 83         /*for(i=1;i<=n;i++)
 84         {
 85             for(j=1;j<=n;j++)
 86                 printf("%d ",map[i][j]);
 87             printf("
");
 88         }*/
 89         km();
 90         int flag=1;
 91         int res=0;
 92         for(i=1;i<=n;i++)
 93         {
 94             if(map[match[i]][i]==-INF)
 95             {flag=0;break;}
 96             else res+=map[match[i]][i];
 97         }
 98         if(!flag)printf("-1
");
 99         else
100          printf("%d
",-res);
101     }
102 }