Rokua P3381 "template" Minimum cost maximum flow

Topic Links:

https://www.luogu.org/problem/show?pid=3381

Main topic:

Maximum flow and cost flow

Topic Ideas:

Minimum cost maximum flow template questions, notes are marked in the template.

Code:

#include <bits/stdc++.h> using namespace std;  
int n,m;  int s,t;  S is the source point T is the sink-point const int MAXN = 5010;  The maximum value of the point const int MAXM = 100100;  The maximum value of the edge of the const int INF = 0x7fffffff;  
    INF open error may be t struct edge{int to,next,cap,flow;  
int cost;  

} EDGE[MAXM];  
int head[maxn],tol;  
int PRE[MAXN];  
int DIS[MAXN];  
BOOL VIS[MAXN];  
int N;   void init ()//Do not forget init () {N = n+10;  
    Do not open too large may be t tol = 0;
	memset (head,-1,sizeof (head));  s=0;//Source Point Super Source Point can set its own//t=n+1; Meeting point, I'm driving here. N+10 The result is timed out, the unknown Li Super meeting point can set its own} void Addedge (int u,int v,int cap,double cost)//build edge, cap is capacity cost is expense {edge  
    [tol].to = v;  
    Edge[tol].cap = cap;  
    Edge[tol].cost = Cost;  
    Edge[tol].flow = 0;  
    Edge[tol].next = Head[u];  
    Head[u] = tol++;  
    edge[tol].to = u;  
    Edge[tol].cap = 0;  
    Edge[tol].cost =-cost;  
    Edge[tol].flow = 0;  
    Edge[tol].next = Head[v];  
HEAD[V] = tol++; } bool SPFA (int s,int t)//s is the source point T is the sink point {QUEUE&Lt;int>q;  
        for (int i = 0; i < N; i++) {dis[i] = INF;  
        Vis[i] = false;  
    Pre[i] =-1;  
    } Dis[s] = 0;  
    Vis[s] = true;  
    Q.push (s);  
        while (!q.empty ()) {int u = q.front ();  
        Q.pop ();  
        Vis[u] = false;  
            for (int i = head[u]; i =-1; i = edge[i].next) {int v = edge[i].to; 
                if (Edge[i].cap > Edge[i].flow && dis[v]-dis[u]-edge[i].cost>0) {//floating-point number plus precision judgment, otherwise it will T  
                DIS[V] = Dis[u] + edge[i].cost;  
                PRE[V] = i;  
                    if (!vis[v]) {Vis[v] = true;  
                Q.push (v);  
    }}}} if (pre[t] = = 1) return false;  
else return true;  
    } int mincostmaxflow (int s,int t,int &cost) {//cost returns the minimum charge int flow = 0;//flow returns the maximum stream cost = 0; while (SPFA (s,t)) {int Min = INF;  
                    for (int i = pre[t]; i =-1; i = pre[edge[i^1].to]) {if (Min > Edge[i].cap-edge[i].flow)  
        Min = Edge[i].cap-edge[i].flow;  
            } for (int i = pre[t]; i =-1; i = pre[edge[i^1].to]) {edge[i].flow + = Min;  
            Edge[i^1].flow = Min;  
        Cost + = Edge[i].cost * Min;  
    } flow + = Min;  } return flow;
    Find out Max stream} int main () {scanf ("%d%d%d%d", &n,&m,&s,&t);
    	Init ();//Do not forget the init for (int i=1;i<=m;i++) {int ui,vi,wi,fi; scanf ("%d%d%d%d", &ui,&vi,&wi,&fi);//For the maximum fee, ****************** only need to take the opposite number of costs ********************
	* Addedge (UI,VI,WI,FI);
	} int Ans=0;//ans is the minimum cost printf ("%d", Mincostmaxflow (S,t,ans));
    printf ("%d\n", ans);  
return 0;   }