const int INF = 0x3f3f3f3f;
const int MAXN = ;
struct Edge{
int value,flow,to,rev;
Edge(){}
Edge(int a,int b,int c,int d):to(a),value(b),flow(c),rev(d){}
};
vector<Edge> E[MAXN];
inline void Add(int from,int to,int flow,int value){
E[from].push_back(Edge(to,value,flow,E[to].size()));
E[to].push_back(Edge(from,-value,0,E[from].size()-1));
}
bool book[MAXN];//用于SPFA中标记是否在queue中
int cost[MAXN];//存费用的最短路径
int pre[MAXN];//存前节点
int pree[MAXN];//存在前节点的vector中的下标
bool Spfa(int from,int to){
memset(book,false,sizeof book);
memset(cost,INF,sizeof cost);
book[from] = true;
cost[from] = 0;
queue<int> Q;
Q.push(from);
while(!Q.empty()){
int t = Q.front();
book[t] = false;
Q.pop();
for(int i=0 ; i<E[t].size() ; ++i){
Edge& e = E[t][i];
if(e.flow > 0 && cost[e.to] > cost[t] + e.value){
cost[e.to] = cost[t] + e.value;
pre[e.to] = t;
pree[e.to] = i;
if(book[e.to] == false){
Q.push(e.to);
book[e.to] = true;
}
}
}
}
return cost[to] != INF;
}
int Work(int from,int to){
int sum = 0;
while(Spfa(from,to)){
int mflow = INF;//SPFA找到的最短路径的最小容量
int flag = to;
while(flag != from){
mflow = min(mflow,E[pre[flag]][pree[flag]].flow);
flag = pre[flag];
}
flag = to;
while(flag != from){
sum += E[pre[flag]][pree[flag]].value * mflow;
E[pre[flag]][pree[flag]].flow -= mflow;
E[flag][E[pre[flag]][pree[flag]].rev].flow += mflow;
flag = pre[flag];
}
}
return sum;//返回费用
}