BAOVE - Bảo vệ
Tác giả: skyvn97
Ngôn ngữ: C++
#include<bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<=(b);i=i+1)
#define REP(i,n) for (int i=0;i<(n);i=i+1)
#define FORE(i,v) for (__typeof((v).begin()) i=(v).begin();i!=(v).end();i++)
using namespace std;
const int INF=(int)1e9+7;
class DinicFlow {
private:
vector<int> dist,head,q,work;
vector<int> capa,flow,next,point;
int n,m;
public:
DinicFlow() {
n=0;m=0;
}
DinicFlow(int n) {
this->n=n;
this->m=0;
dist=vector<int>(n+7);
head=vector<int>(n+7,-1);
q=vector<int>(n+7);
work=vector<int>(n+7);
}
void addedge(int u,int v,int c1,int c2) {
point.push_back(v);capa.push_back(c1);flow.push_back(0);next.push_back(head[u]);head[u]=m;m++;
point.push_back(u);capa.push_back(c2);flow.push_back(0);next.push_back(head[v]);head[v]=m;m++;
}
bool bfs(int s,int t) {
FOR(i,1,n) dist[i]=-1;
int sz=1;
q[0]=s;dist[s]=0;
REP(x,sz) {
int u=q[x];
for (int i=head[u];i>=0;i=next[i])
if (dist[point[i]]<0 && flow[i]<capa[i]) {
dist[point[i]]=dist[u]+1;
q[sz]=point[i];
sz++;
}
}
return (dist[t]>=0);
}
int dfs(int s,int t,int f) {
if (s==t) return (f);
for (int &i=work[s];i>=0;i=next[i])
if (dist[point[i]]==dist[s]+1 && flow[i]<capa[i]) {
int d=dfs(point[i],t,min(f,capa[i]-flow[i]));
if (d>0) {
flow[i]+=d;
flow[i^1]-=d;
return (d);
}
}
return (0);
}
int maxflow(int s,int t) {
int totflow=0;
while (bfs(s,t)) {
FOR(i,1,n) work[i]=head[i];
while (true) {
int d=dfs(s,t,INF);
if (d<=0) break;
totflow+=d;
}
}
return (totflow);
}
};
int n;
DinicFlow G;
void process(void) {
scanf("%d",&n);
G=DinicFlow(n);
int u,v,d;
while (scanf("%d%d%d",&u,&v,&d)==3) G.addedge(u,v,d,0);
cerr << 123 << endl;
printf("%d",G.maxflow(n,1));
}
int main(void) {
#ifndef ONLINE_JUDGE
freopen("tmp.txt","r",stdin);
#endif
process();
return 0;
}