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| #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int maxn = 1e5+5;
const int INF = 0x3f3f3f3f;
struct Edge
{
int from,to,cap,flow;
Edge(){}
Edge(int u,int v,int c,int f):from(u),to(v),cap(c),flow(f){}
};
struct Dinic
{
int n,m,s,t;
vector<Edge> edges;
vector<int> G[maxn];
bool vis[maxn];
int d[maxn];
int cur[maxn];
void init(int n){
for(int i=0;i<n;i++) G[i].clear();
edges.clear();
}
void AddEdge(int from,int to,int cap){
edges.push_back(Edge(from,to,cap,0));
edges.push_back(Edge(to,from,0,0));
m = edges.size();
G[from].push_back(m-2);
G[to].push_back(m-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 s,int t){
this->s = s,this->t = t;
int flow = 0;
while(BFS()){
memset(cur,0,sizeof(cur));
flow += DFS(s,INF);
}
return flow;
}
};
vector<Edge> G1[maxn];
vector<Edge> G2[maxn];
int N,M;
int dis[maxn],dis2[maxn];
bool vis[maxn];
void dijkstra(int A,vector<Edge> G[maxn],int dis[maxn])
{
memset(vis,0,sizeof(vis));
priority_queue<pii,vector<pii>,greater<pii> > Q;
dis[A] = 0;
Q.push(pii(dis[A],A));
while(!Q.empty()){
pii t = Q.top();
Q.pop();
int d = t.first;
int u = t.second;
for(int i=0;i<G[u].size();i++){
Edge e = G[u][i];
if(e.cap + d < dis[e.to]){
dis[e.to] = e.cap + d;
Q.push(pii(dis[e.to],e.to));
}
}
}
}
int main(int argc, char const *argv[])
{
ios::sync_with_stdio(false);
cin.tie(0);
int T = 0;
cin >> T;
Dinic ek;
while(T--){
cin >> N >> M;
ek.init(N);
for(int i=0;i<=N;i++){
G1[i].clear();
G2[i].clear();
}
int a,b,c;
Edge e;
for(int i=0;i<M;i++){
cin >> a >> b >> c;
e.from = a;
e.to = b;
e.cap = c;
G1[e.from].push_back(e);
swap(e.to,e.from);
G2[e.from].push_back(e);
}
int A,B;
cin >> A >> B;
memset(dis,0x3f,sizeof(dis));
dijkstra(A,G1,dis);
memset(dis2,0x3f,sizeof(dis2));
int Min = dis[B];
dijkstra(B,G2,dis2);
for(int i=1;i<=N;i++){
for(int j=0;j<G1[i].size();j++){
e = G1[i][j];
if(dis[e.from] + e.cap + dis2[e.to]==Min){
ek.AddEdge(e.from,e.to,1);
}
}
}
cout << ek.Maxflow(A,B) << endl;
}
return 0;
}
|
