#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<iostream>
using namespace std;
const int MAXN=100010;//点数的最大值
const int MAXM=400010;//边数的最大值
const int INF=0x3f3f3f3f;
struct Node
{
int from,to,next;
int cap;
}edge[MAXM];
int tol;
int head[MAXN];
int dep[MAXN];
int gap[MAXN];//gap[x]=y :说明残留网络中dep[i]==x的个数为y
int n;//n是总的点的个数,包括源点和汇点
void init()
{
tol=0;
memset(head,-1,sizeof(head));
}
void addedge(int u,int v,int w)
{
edge[tol].from=u;
edge[tol].to=v;
edge[tol].cap=w;
edge[tol].next=head[u];
head[u]=tol++;
edge[tol].from=v;
edge[tol].to=u;
edge[tol].cap=0;
edge[tol].next=head[v];
head[v]=tol++;
}
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].next)
{
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 SAP(int start,int end)
{
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].next)
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].next)
{
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;
}
int main()
{
int _,m;
int wx,ex,u,v,c,s,t;
scanf("%d",&_);
while(_--)
{
init();
scanf("%d%d",&n,&m);
wx=1<<24;
ex=-1<<24;
for(int i=1; i<=n; i++)
{
scanf("%d%d",&u,&v);
if(wx>u)
{
wx=u;
s=i;
}
if(ex<u)
{
ex=u;
t=i;
}
}
for(int i=0; i<m; i++)
{
scanf("%d%d%d",&u,&v,&c);
addedge(u,v,c);
addedge(v,u,c);
}
printf("%d\n",SAP(s,t));
}
return 0;
}
超时的
/poj 1273 ×î´óÁ÷
#include<stdio.h>
#include<string.h>
#include<queue>
#include<vector>
#pragma comment(linker, "/STACK:1024000000,1024000000")//外挂开栈
using namespace std;
const int N=100000+5;
const int inf=1<<24;
struct Edge
{
int from,to,cap,flow;
};
vector<Edge>edges;
vector<int>G[N];
int n,m,s,t;
int vis[N];
int d[N];
int cur[N];
void AddEdge(int from,int to,int cap)
{
Edge tp;
tp.from=from,tp.to=to,tp.cap=cap,tp.flow=0;
edges.push_back(tp);
tp.from=to,tp.to=from,tp.cap=0,tp.flow=0;
edges.push_back(tp);
int g_size=edges.size();
G[from].push_back(g_size-2);
G[to].push_back(g_size-1);
}
bool BFS()
{
memset(vis,0,sizeof(vis));
queue<int>Q;
Q.push(s);
d[s]=0;
vis[s]=1;
while(!Q.empty())
{
int x=Q.front();
Q.pop();
for(int i=0; i<G[x].size(); i++)
{
Edge &e=edges[G[x][i]];
if(!vis[e.to]&&e.cap>e.flow)
{
vis[e.to]=1;
d[e.to]=d[x]+1;
Q.push(e.to);
}
}
}
return vis[t];
}
int DFS(int x,int a)
{
if(x==t||a==0) return a;
int flow=0,f;
for(int &i=cur[x]; i<G[x].size(); i++)
{
Edge &e=edges[G[x][i]];
if(d[x]+1==d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>0)
{
e.flow+=f;
edges[G[x][i]^1].flow-=f;
flow+=f;
a-=f;
if(a==0) break;
}
}
return flow;
}
int Maxflow(int st,int ed)
{
int flow=0;
while(BFS())
{
memset(cur,0,sizeof(cur));
flow+=DFS(st,inf);
}
return flow;
}
int main()
{
int _;
int wx,ex,u,v,c;
scanf("%d",&_);
while(_--)
{
scanf("%d%d",&n,&m);
edges.clear();
for(int i=0; i<N; i++)
G[i].clear();
wx=1<<24;
ex=-1<<24;
for(int i=1; i<=n; i++)
{
scanf("%d%d",&u,&v);
if(wx>u)
{
wx=u;
s=i;
}
if(ex<u)
{
ex=u;
t=i;
}
}
for(int i=0; i<m; i++)
{
scanf("%d%d%d",&u,&v,&c);
AddEdge(u,v,c);
AddEdge(v,u,c);
}
//printf("%d %d\n",s,t);
printf("%d\n",Maxflow(s,t));
}
return 0;
}
#include<bits/stdc++.h>
using namespace std;
const int MAXN = 100009;//点数的最大值
const int MAXM = 100009;//边数的最大值
const int INF = 0x3f3f3f3f;
struct Edge
{
int to,next,cap,flow;
} edge[MAXM]; //注意是MAXM
int tol;
int head[MAXN];
int gap[MAXN],dep[MAXN],cur[MAXN];
void init()
{
tol = 0;
memset(head,-1,sizeof(head));
}
void addedge(int u,int v,int w)
{
int rw = 0;
edge[tol].to = v;
edge[tol].cap = w;
edge[tol].flow = 0;
edge[tol].next = head[u];
head[u] = tol++;
edge[tol].to = u;
edge[tol].cap = rw;
edge[tol].flow = 0;
edge[tol].next = head[v];
head[v] = tol++;
}
int Q[MAXN];
void BFS(int start,int end)
{
memset(dep,-1,sizeof(dep));
memset(gap,0,sizeof(gap));
gap[0] = 1;
int front = 0, rear = 0;
dep[end] = 0;
Q[rear++] = end;
while(front != rear)
{
int u = Q[front++];
for(int i = head[u]; i != -1; i = edge[i].next)
{
int v = edge[i].to;
if(dep[v] != -1)continue;
Q[rear++] = v;
dep[v] = dep[u] + 1;
gap[dep[v]]++;
}
}
}
int S[MAXN];
int sap(int start,int end,int N)
{
BFS(start,end);
memcpy(cur,head,sizeof(head));
int top = 0;
int u = start;
int ans = 0;
while(dep[start] < N)
{
if(u == end)
{
int Min = INF;
int inser;
for(int i = 0; i < top; i++)
if(Min > edge[S[i]].cap - edge[S[i]].flow)
{
Min = edge[S[i]].cap - edge[S[i]].flow;
inser = i;
}
for(int i = 0; i < top; i++)
{
edge[S[i]].flow += Min;
edge[S[i]^1].flow -= Min;
}
ans += Min;
top = inser;
u = edge[S[top]^1].to;
continue;
}
bool flag = false;
int v;
for(int i = cur[u]; i != -1; i = edge[i].next)
{
v = edge[i].to;
if(edge[i].cap - edge[i].flow && dep[v]+1 == dep[u])
{
flag = true;
cur[u] = i;
break;
}
}
if(flag)
{
S[top++] = cur[u];
u = v;
continue;
}
int Min = N;
for(int i = head[u]; i != -1; i = edge[i].next)
if(edge[i].cap - edge[i].flow && dep[edge[i].to] < Min)
{
Min = dep[edge[i].to];
cur[u] = i;
}
gap[dep[u]]--;
if(!gap[dep[u]])return ans;
dep[u] = Min + 1;
gap[dep[u]]++;
if(u != start)u = edge[S[--top]^1].to;
}
return ans;
}
int main()
{
int _,n,m;
int wx,ex,u,v,c,s,t;
scanf("%d",&_);
while(_--)
{
init();
scanf("%d%d",&n,&m);
wx=1<<24;
ex=-1<<24;
for(int i=1; i<=n; i++)
{
scanf("%d%d",&u,&v);
if(wx>u)
{
wx=u;
s=i;
}
if(ex<u)
{
ex=u;
t=i;
}
}
for(int i=0; i<m; i++)
{
scanf("%d%d%d",&u,&v,&c);
addedge(u,v,c);
addedge(v,u,c);
}
//printf("%d %d\n",s,t);
printf("%d\n",sap(s,t,n));
}
return 0;
}