//sap算法+bfs初始化+栈优化
#include<bits/stdc++.h>
using namespace std;
const int maxn=100010;
const int maxm=400010;
const int inf=0x3f3f3f3f;
struct edge
{
int from,to,nxt,cap,flow;
}edge[maxm];
int cnt,head[maxn];
int gap[maxn],dep[maxn],cur[maxn];
void init()
{
cnt=0;
memset(head,-1,sizeof(head));
}
void add_edge(int u,int v,int w,int rw=0)
{
edge[cnt].from=u;
edge[cnt].to=v;
edge[cnt].cap=w;
edge[cnt].nxt=head[u];
edge[cnt].flow=0;
head[u]=cnt++;
edge[cnt].from=v;
edge[cnt].to=u;
edge[cnt].cap=rw;
edge[cnt].flow=0;
edge[cnt].nxt=head[v];
head[v]=cnt++;
}
int q[maxn];
void bfs(int start,int end)
{
memset(dep,-1,sizeof(dep));
memset(gap,0,sizeof(gap));
gap[0]=1;
int que[maxn];
int front,rear;
front=rear=0;
dep[end]=0;
que[rear++]=end;
while(front!=rear)
{
int u=que[front++];
if(front==maxn)front=0;
for(int i=head[u];i!=-1;i=edge[i].nxt)
{
int v=edge[i].to;
if(dep[v]!=-1)continue;
que[rear++]=v;
if(rear==maxn)rear=0;
dep[v]=dep[u]+1;
++gap[dep[v]];
}
}
}
int s[maxn];
int sap(int start,int end,int n)
{
int res=0;
bfs(start,end);
int cur[maxn];
int S[maxn];
int top=0;
memcpy(cur,head,sizeof(head));
int u=start;
int i;
while(dep[start]<n)
{
if(u==end)
{
int temp=inf;
int inser;
for(i=0;i<top;i++)
if(temp>edge[S[i]].cap)
{
temp=edge[S[i]].cap;
inser=i;
}
for(i=0;i<top;i++)
{
edge[S[i]].cap-=temp;
edge[S[i]^1].cap+=temp;
}
res+=temp;
top=inser;
u=edge[S[top]].from;
}
if(u!=end&&gap[dep[u]-1]==0)//出现断层,无增广路
break;
for(i=cur[u];i!=-1;i=edge[i].nxt)
if(edge[i].cap!=0&&dep[u]==dep[edge[i].to]+1)
break;
if(i!=-1)
{
cur[u]=i;
S[top++]=i;
u=edge[i].to;
}
else
{
int min=n;
for(i=head[u];i!=-1;i=edge[i].nxt)
{
if(edge[i].cap==0)continue;
if(min>dep[edge[i].to])
{
min=dep[edge[i].to];
cur[u]=i;
}
}
--gap[dep[u]];
dep[u]=min+1;
++gap[dep[u]];
if(u!=start)u=edge[S[--top]].from;
}
}
return res;
}
struct node
{
int x,y;
int id;
}a[maxn*4];
int main ()
{
int t;
scanf("%d",&t);
while(t--)
{
int n,m;
memset(head,-1,sizeof(head));
cnt=0;
scanf("%d%d",&n,&m);
int maxx=-inf,minn=inf;
int max_pos=1,min_pos=1;
for(int i=1;i<=n;i++)
{
scanf("%d%d",&a[i].x,&a[i].y);
a[i].id=i;
if(a[i].x>maxx)
{
maxx=a[i].x;
max_pos=a[i].id;
}
if(a[i].x<minn)
{
minn=a[i].x;
min_pos=a[i].id;
}
}
for(int i=1;i<=m;i++)
{
int xx,yy,zz;
scanf("%d%d%d",&xx,&yy,&zz);
add_edge(xx,yy,zz);
add_edge(yy,xx,zz);
}
//printf("%d %d\n",a[1].id,a[n].id);
int res=sap(min_pos,max_pos,n);
printf("%d\n",res);
}
}
sap+bfs初始化+栈优化 应用于点和边在十万左右
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转载自blog.csdn.net/qq_36616023/article/details/80287019
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