# 最小费用最大流 + dijkstra 模版(处理负边)

```#pragma GCC optimize(2)
#include <iostream>
#include <algorithm>
#include <queue>
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#define MAXN_ 5050
#define INF 0x3f3f3f3f
#define P pair<int,int>
using namespace std;
struct edge{ int to,cap,cost,rev;};
int n,m,flow,s,t,cap,res,cost,from,to,h[MAXN_];
std::vector<edge> G[MAXN_];
int dist[MAXN_],prevv[MAXN_],preve[MAXN_]; // 前驱节点和对应边
{
G[from].push_back((edge){to,cap,cost,(int)G[to].size()});
G[to].push_back((edge){from,0,-cost,(int)G[from].size()-1});
} // 在vector 之中找到边的位置所在!
{
int x=0;
char c=getchar();
bool flag=0;
while(c<'0'||c>'9'){if(c=='-')flag=1;    c=getchar();}
while(c>='0'&&c<='9'){x=(x<<3)+(x<<1)+c-'0';c=getchar();}
return flag?-x:x;
}
inline void min_cost_flow(int s,int t,int f)
{
fill(h+1,h+1+n,0);
while(f > 0)
{
priority_queue<P,vector<P>, greater<P> > D;
memset(dist,INF,sizeof dist);
dist[s] = 0; D.push(P(0,s));
while(!D.empty())
{
P now = D.top(); D.pop();
if(dist[now.second] < now.first) continue;
int v = now.second;
for(int i=0;i<(int)G[v].size();++i)
{
edge &e = G[v][i];
if(e.cap > 0 && dist[e.to] > dist[v] + e.cost + h[v] - h[e.to])
{
dist[e.to] = dist[v] + e.cost + h[v] - h[e.to];
prevv[e.to] = v;
preve[e.to] = i;
D.push(P(dist[e.to],e.to));
}
}
}
// 无法增广 ， 就是找到了答案了！
if(dist[t] == INF) break;
for(int i=1;i<=n;++i) h[i] += dist[i];
int d = f;
for(int v = t; v != s; v = prevv[v])
d = min(d,G[prevv[v]][preve[v]].cap);
f -= d; flow += d;
res += d * h[t];
for(int v=t;v!=s;v=prevv[v])
{
edge &e = G[prevv[v]][preve[v]];
e.cap -= d;
G[v][e.rev].cap += d;
}
}
}
int main()
{
for(int i=1;i<=m;++i)
{
}
min_cost_flow(s,t,INF);
printf("%d %d\n",flow,res);
return 0;
}```

0 条评论