> 
> //	Accepted	808K	391MS	C++	2314B	2012-09-12 09:27:43
> #include<stdio.h>
> #include<stdlib.h>
> #include<string.h>
> #define inf 10000000
> struct node 
> {
> 	int u,v,w;
> }edge[40010];
> int n,p,t,vist[210],opt[210],cf[210][210],dui[210];
> void creat(int l)
> {
> 	int i;
> 	 memset(cf,0,sizeof(cf));
>      for(i=1;i<=l;i++)
> 	 {
> 		 cf[edge[i].u][edge[i].v]++;
> 		 cf[edge[i].v][edge[i].u]=cf[edge[i].u][edge[i].v];
> 	 }
> 	 return;
> }
> int bfs() 
> { 
>     memset(vist,0,sizeof(vist)); 
>     memset(opt,0,sizeof(opt)); 
>     int rear=0,front=0,x,i; 
>     opt[1]=0; 
>     vist[1]=1; 
>     dui[rear]=1; 
>     front++; 
>     while(rear!=front) 
>     { 
>         x=dui[rear]; 
>         rear++; 
>         for(i=1;i<=n;i++) 
>         { 
>             if(vist[i]==0&&cf[x][i]>0) 
>             { 
>                 vist[i]=1; 
>                 dui[front]=i; 
>                 front++; 
>                 opt[i]=opt[x]+1; 
>             } 
>         } 
>     } 
>     if(vist[n]==1) 
>     { 
>         return 1; 
>     } 
>     else
>     { 
>         return 0; 
>     } 
> } 
> int flow; 
> int min(int a,int b)
> {
> 	if(a<b)  return a;
> 	else   return b;
> }
> int dfs(int x,int cp) 
> { 
>     int i,tem,cmp; 
>     tem=cp;
>     if(x==n) 
>     { 
>         
>         flow+=cp; 
>         return cp; 
>     } 
>         for(i=1;i<=n;i++) 
>         { 
>             if(opt[x]==opt[i]-1&&cf[x][i]>0) 
>             { 
>                 cmp=dfs(i,min(cf[x][i],tem)); 
> 				cf[x][i]-=cmp;
> 				cf[i][x]+=cmp;
> 				tem-=cmp;
>             } 
>         } 
>     return cp-tem; 
> } 
> int dinic()
> {
> 	int zf=0;
> 	while(bfs())
> 	{
> 		flow=0;
> 		dfs(1,inf);
>         zf+=flow;
> 	}
> 	return zf;
> }
> int cmp(const void *a,const void *b)
> {
> 	struct node *x=(node *)a;
> 	struct node *y=(node *)b;
> 	return (x->w)-(y->w);
> }
> int main()
> {
> 	int i,j,right,left,mid,high,liu;
> 	scanf("%d%d%d",&n,&p,&t);
> 	for(i=1;i<=p;i++)
> 	{
> 		scanf("%d%d%d",&edge[i].u,&edge[i].v,&edge[i].w);
> 	}
>     qsort(edge+1,p,sizeof(struct node),cmp);
>     /*for(i=1;i<=p;i++)
> 	{
> 	    printf("%d %d %d\n",edge[i].u,edge[i].v,edge[i].w);
> 	}*/  //correct
> 	left=1;
> 	right=p;
> 	high=inf;
> 	while(left<=right)
> 	{
> 		mid=(left+right)/2;
> 		creat(mid);
> 		liu=dinic();
> 		if(liu>=t)
> 		{
> 			if(edge[mid].w<high)
> 			{
> 				high=edge[mid].w;
> 			}
> 			right=mid-1;
> 		}
> 		else
> 		{
>            left=mid+1;
> 		}
> 	}
> 	printf("%d\n",high);
> 	return 0;
> }

这个二分边太精辟了！少做很多次流，构图也快些