题意：从1到n，要走不少于K条路，每条路不能重复走，点可以重复走，求所走的路中最长的最小，，

找出距离的最大值，然后二分，建图时符合的每条边链接的两点间建双向边，流量都为1，求最大流

#include
#include
const int N=210;
const int inf=0x3fffffff;
int dis[N],gap[N],head[N],num,start,end,ans,n,m;
struct edge
{
	int st,ed,flow,next;
}E[200000];
struct node
{
	int x,y,w;
}P[40000];
void addedge(int x,int y,int w)
{
	E[num].st=x;E[num].ed=y;E[num].flow=w;E[num].next=head[x];head[x]=num++;
	E[num].st=y;E[num].ed=x;E[num].flow=w;E[num].next=head[y];head[y]=num++;
}
void makemap(int D)
{
	memset(head,-1,sizeof(head));
	num=0;
	int i;
	for(i=0;iminflow-flow minflow-flow:E[i].flow);
				E[i].flow-=f;
				E[i^1].flow+=f;
				flow+=f;
				if(flow==minflow)break;
				if(dis[start]>=ans)return flow;
			}
			min_dis=min_dis>dis[v] dis[v]:min_dis;
		}
	}
	if(flow==0)
	{
		if(--gap[dis[u]]==0)
			dis[start]=ans;
		dis[u]=min_dis+1;
		gap[dis[u]]++;
	}
	return flow;
}
int isap()
{
	int maxflow=0;
	memset(dis,0,sizeof(dis));
	memset(gap,0,sizeof(gap));
	gap[0]=ans;
	while(dis[start]=k)
			   R=mid;
		   else L=mid+1;
		}
		printf("%d\n",R);
	}
	return 0;
}