最小费用流spfa算法模板（pascal）

 1 program rrr(input,output);
 2 const
 3   inf=123456789;
 4 type
 5   etype=record
 6      t,c,w,next,rev:longint;
 7   end;
 8 var
 9   e:array[0..100010]of etype;
10   a,fre,frv,q,dis:array[0..5050]of longint;
11   inq:array[0..5050]of boolean;
12   n,m,s,t,i,j,x,y,c,w,max,ans,cnt,f:longint;
13 procedure add(x,y,c,w:longint);
14 begin
15    inc(cnt);e[cnt].t:=y;e[cnt].c:=c;e[cnt].w:=w;e[cnt].next:=a[x];a[x]:=cnt;
16 end;
17 function min(a,b:longint):longint;
18 begin
19    if a<b then exit(a) else exit(b);
20 end;
21 procedure spfa;
22 var
23   h,t:longint;
24 begin
25    for i:=1 to n do dis[i]:=inf;
26    fillchar(inq,sizeof(inq),false);
27    h:=0;t:=1;q[1]:=s;dis[s]:=0;inq[s]:=true;
28    while h<>t do
29       begin
30          inc(h);if h>5000 then h:=1;
31          i:=a[q[h]];
32          while i<>0 do
33             begin
34                if (e[i].c>0) and (dis[q[h]]+e[i].w<dis[e[i].t]) then
35                   begin
36                      dis[e[i].t]:=dis[q[h]]+e[i].w;
37                      frv[e[i].t]:=q[h];fre[e[i].t]:=i;
38                      if not inq[e[i].t] then
39                         begin
40                            inc(t);if t>5000 then t:=1;
41                            q[t]:=e[i].t;inq[e[i].t]:=true;
42                         end;
43                   end;
44                i:=e[i].next;
45             end;
46          inq[q[h]]:=false;
47       end;
48 end;
49 begin
50    assign(input,‘r.in‘);assign(output,‘r.out‘);reset(input);rewrite(output);
51    readln(n,m,s,t);
52    fillchar(a,sizeof(a),0);cnt:=0;
53    for i:=1 to m do
54       begin
55          readln(x,y,c,w);
56          add(x,y,c,w);e[cnt].rev:=cnt+1;
57          add(y,x,0,-w);e[cnt].rev:=cnt-1;
58       end;
59    max:=0;ans:=0;
60    while true do
61       begin
62          spfa;
63          if dis[t]=inf then break;
64          j:=t;f:=inf;
65          while j<>s do begin f:=min(f,e[fre[j]].c);j:=frv[j]; end;
66          max:=max+f;
67          j:=t;w:=0;
68          while j<>s do begin w:=w+e[fre[j]].w;dec(e[fre[j]].c,f);inc(e[e[fre[j]].rev].c,f);j:=frv[j]; end;
69          ans:=ans+w*f;
70       end;
71    write(max,‘ ‘,ans);
72    close(input);close(output);
73 end.