每次选代价最小的流增广
#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;
struct Edge{
int too, nxt, val, cst;
}edge[100005];
int n, m, ss, tt, maxFlow, minCost, uu, vv, ww, xx, hea[5005], cnt;
int dis[5005], pre[5005];
bool vis[5005];
const int oo=0x3f3f3f3f;
queue<int> d;
void add_edge(int fro, int too, int val, int cst){
edge[cnt].nxt = hea[fro];
edge[cnt].too = too;
edge[cnt].val = val;
edge[cnt].cst = cst;
hea[fro] = cnt++;
}
bool spfa(){
memset(dis, 0x3f, sizeof(dis));
memset(pre, -1, sizeof(pre));
dis[ss] = 0;
d.push(ss);
vis[ss] = true;
while(!d.empty()){
int x=d.front();
d.pop();
vis[x] = false;
for(int i=hea[x]; i!=-1; i=edge[i].nxt){
int t=edge[i].too;
if(dis[t]>dis[x]+edge[i].cst && edge[i].val>0){
dis[t] = dis[x] + edge[i].cst;
pre[t] = i;
if(!vis[t]){
vis[t] = true;
d.push(t);
}
}
}
}
return dis[tt]!=oo;
}
void mcmf(){
while(spfa()){
int tmp=oo;
for(int i=pre[tt]; i!=-1; i=pre[edge[i^1].too])
tmp = min(tmp, edge[i].val);
for(int i=pre[tt]; i!=-1; i=pre[edge[i^1].too]){
edge[i].val -= tmp;
edge[i^1].val += tmp;
minCost += edge[i].cst * tmp;
}
maxFlow += tmp;
}
}
int main(){
cin>>n>>m>>ss>>tt;
memset(hea, -1, sizeof(hea));
for(int i=1; i<=m; i++){
scanf("%d %d %d %d", &uu, &vv, &ww, &xx);
add_edge(uu, vv, ww, xx);
add_edge(vv, uu, 0, -xx);
}
mcmf();
cout<<maxFlow<<" "<<minCost<<endl;
return 0;
}