完全二部图匹配

给出一个完全二部图，每个配对都有一个附加值，求最大附加值最小的完美匹配。

#include<string.h>#include<cstdio>#include<cstdlib>using namespace std;const int maxn=1001;int N;int disp[maxn][maxn];int heightm[maxn];int agem[maxn];int heightw[maxn];int agew[maxn];int nx,ny,g[maxn][maxn],sy[maxn],cx[maxn],cy[maxn];int path(int u){for(int v=1;v<=ny;v++)if(g[u][v]&&!sy[v]){sy[v]=1;if(!cy[v]||path(cy[v])){cx[u]=v;cy[v]=u;return 1;}}return 0;}int maxmatch(){int i,ret=0;memset(cx,0,sizeof(cx));memset(cy,0,sizeof(cy));for(i=1;i<=nx;i++)    {memset(sy,0,sizeof(sy));ret+=path(i);}return ret;}void buildgraph(int x){int i,j;nx=ny=N;memset(g,0,sizeof(g));for(i=1;i<=N;i++){for(j=1;j<=N;j++){if(disp[i][j]<=x)g[i][j]=1;else  g[i][j]=0;}}}int main(){int i,j,p,q,ans,left,right;while(scanf("%d",&N)==1){if(N==0)break;for(i=1;i<=N;i++){scanf("%d%d",&heightm[i],&agem[i]);}for(i=1;i<=N;i++){scanf("%d%d",&heightw[i],&agew[i]);}left=1000000000;right=0;for(i=1;i<=N;i++){for(j=1;j<=N;j++){p=heightm[i]-heightw[j];q=agem[i]-agew[j];disp[i][j]=p*p+q*q;if(disp[i][j]<left)left=disp[i][j];if(disp[i][j]>right)right=disp[i][j];}}while(left<=right){int mid=(left+right)/2;buildgraph(mid);int ret=maxmatch();if(ret==N){ans=mid;right=mid-1;}else{left=mid+1;}}printf("%d\n",ans);}return 0;}