大神总结：http://www.cnblogs.com/skyming/archive/2012/02/18/2356919.html
代码：
1 #include<stdio.h> 2 #include<string.h> 3 const int N=555,INF=0x3f3f3f3f; 4 int lx[N],ly[N],vx[N],vy[N],slack[N],match[N]; 5 int a[N][N]; 6 int nx,ny; 7 int dfs(int u) 8 { 9 vx[u]=1; 10 for(int i=1;i<=ny;i++) 11 { 12 if(vy[i]) continue; 13 int t=lx[u]+ly[i]-a[u][i]; 14 if(t==0) 15 { 16 vy[i]=1; 17 if(match[i]==-1||dfs(match[i])) 18 { 19 match[i]=u; 20 return 1; 21 } 22 } 23 else if(slack[i]>t) 24 slack[i]=t; 25 } 26 return 0; 27 } 28 int KM() 29 { 30 int i,j,d; 31 memset(ly,0,sizeof(ly)); 32 memset(match,-1,sizeof(match)); 33 for(i=1,lx[i]=-INF;i<=nx;i++) 34 for(j=1;j<=ny;j++) 35 if(a[i][j]>lx[i]) 36 lx[i]=a[i][j]; 37 for(i=1;i<=nx;i++) 38 { 39 memset(slack,0x3f,sizeof(slack)); 40 while(1) 41 { 42 memset(vx,0,sizeof(vx)); 43 memset(vy,0,sizeof(vy)); 44 if(dfs(i)) break; 45 d=INF; 46 for(j=1;j<=ny;j++) 47 if(!vy[j]&&slack[j]<d) 48 d=slack[j]; 49 //if(d==INF) break;//该点找不到任何匹配 50 for(j=1;j<=nx;j++) 51 if(vx[j]) 52 lx[j]-=d; 53 for(j=1;j<=ny;j++) 54 { 55 if(vy[j]) 56 ly[j]+=d; 57 else 58 slack[j]-=d; 59 } 60 } 61 } 62 int ans=0,sum=0; 63 for(i=1;i<=ny;i++) 64 if(match[i]>-1&&a[match[i]][i]) 65 ans+=a[match[i]][i],sum++; 66 printf("%d++ ",sum);//匹配数 67 return ans; 68 } 69 int main() 70 { 71 int m,u,v,w,n,i; 72 scanf("%d",&nx); 73 scanf("%d",&ny); 74 scanf("%d",&m); 75 memset(a,0,sizeof(a)); 76 while(m--) 77 { 78 scanf("%d%d%d",&u,&v,&w); 79 a[u][v]=a[v][u]=w; 80 } 81 printf("%d ",KM()); 82 return 0; 83 }