hdu4280 Island Transport (最大流ISAP算法)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4280

#include 
#include 
#define MAXN 100002
#define MAXE 400002
#define INF 0x3f3f3f3f

struct node
{
	int from,to,next;
	int cap;
}edge[MAXE];

int n,m,tot,src,dest,Queue[MAXN],cur[MAXN],Stack[MAXN];;
int head[MAXN],level[MAXN],gap[MAXN];//gap[x]=y :说明残留网络中level[i]==x的个数为y


void addEdge(int u,int v,int w)
{
	edge[tot].from=u;
	edge[tot].to=v;
	edge[tot].cap=w;
	edge[tot].next=head[u];
	head[u]=tot++;
	edge[tot].from=v;
	edge[tot].to=u;
	edge[tot].cap=0;
	edge[tot].next=head[v];
	head[v]=tot++;
}

void BFS()
{
	int front,rear,i,u,v;
	memset(level,-1,sizeof(level));
	memset(gap,0,sizeof(gap));
	gap[0]=1;//说明此时有1个level[i] = 0
	front=rear=0;
	level[dest]=0;
	Queue[rear++]=dest;
	while(frontedge[Stack[i]].cap)
				{
					temp=edge[Stack[i]].cap;
					inser=i;
				}
			}
			for(i=0;i!=top;++i)
			{
				edge[Stack[i]].cap-=temp;
				edge[Stack[i]^1].cap+=temp;
			}
			maxflow+=temp;
			top=inser;
			u=edge[Stack[top]].from;
		}
		if(u!=dest&&gap[level[u]-1]==0)
			break;//出现断层，无增广路
		for(i=cur[u];i!=-1;i=edge[i].next)
		{//遍历与u相连的未遍历结点
			if(edge[i].cap!=0&&level[u]==level[edge[i].to]+1)//层序关系， 找到允许
				break;
		}
		if(i!=-1)//找到允许弧
		{
			cur[u]=i;
			Stack[top++]=i;//加入路径栈
			u=edge[i].to;//查找下一个结点
		}
		else//无允许的路径，修改标号 当前点的标号比与之相连的点中最小的多1
		{
			int mixn=n;
			for(i=head[u];i!=-1;i=edge[i].next)
			{//找到与u相连的v中level[v]最小的点
				if(edge[i].cap==0)
					continue;
				if(mixn>level[edge[i].to])
				{
					mixn=level[edge[i].to];
					cur[u]=i;//最小标号就是最新的允许弧
				}
			}
			--gap[level[u]];
			level[u]=mixn+1;
			++gap[level[u]];
			if(u!=src)
				u=edge[Stack[--top]].from;
		}
	}
	return maxflow;
}

int main()
{
	int test,ans,i,m,x,y,w;
	int minx,maxx;
	scanf("%d",&test);
	while(test--)
	{
		minx=INF;
		maxx=~INF+1;
		/*n=Scan();
		m=Scan();*/
		scanf("%d %d",&n,&m);
		for(i=1;i<=n;++i)
		{
			/*x=Scan();
			y=Scan();*/
			scanf("%d %d",&x,&y);
			if(minx>=x)
			{
				minx=x;
				src=i;
			}
			if(maxx<=x)
			{
				maxx=x;
				dest=i;
			}
		}
		tot=0;
		memset(head,-1,sizeof(head));
		while(m--)
		{
			/*x=Scan();
			y=Scan();
			w=Scan();*/
			scanf("%d %d %d",&x,&y,&w);
			addEdge(x,y,w);
			addEdge(y,x,w);
		}
		ans=SAP();
		printf("%d\n",ans);
	}
	return 0;
}