3396: [Usaco2009 Jan]Total flow 水流

3396: [Usaco2009 Jan]Total flow 水流

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 179  Solved: 73
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Description

 

Input

第1行输入N，之后N行每行描述一条水管，前两个英文字母表示水管的两端（大小写字母是不一样的），后一个整数表示水管的流量，流量不会超过1000.

Output

一个整数，表示总流量．

Sample Input

5
A B 3
B C 3
C D 5
D Z 4
B Z 6

Sample Output

3

HINT

 

Source

Silver

题解：WA了6次再读题才发现大小写字母不一样TT。别的没了，直接上sap模板A之。。

 type
     point=^node;
     node=record
                g,w:longint;
                next,anti:point;
     end;
 var
    i,j,k,l,m,n,ans,s,t:longint;
    a:array[..] of point;
    d,dv:array[..] of longint;
    c1,c2,c3:char;
 function min(x,y:longint):longint;inline;
          begin
               if x<y then min:=x else min:=y;
          end;
 procedure add(x,y,z:longint);inline;
           var p:point;
           begin
                new(p);p^.g:=y;p^.w:=z;p^.next:=a[x];a[x]:=p;
                new(p);p^.g:=x;p^.w:=;p^.next:=a[y];a[y]:=p;
                a[y]^.anti:=a[x];a[x]^.anti:=a[y];
           end;
 function dfs(x,flow:longint):longint;inline;
          var p:point;k:longint;
          begin
               if x=t then exit(flow);
               dfs:=;p:=a[x];
               while p<>nil do
                     begin
                          if (P^.w>) and (d[x]=(d[p^.g]+)) then
                             begin
                                  k:=dfs(p^.g,min(p^.w,flow-dfs));
                                  dec(p^.w,k);
                                  inc(p^.anti^.w,k);
                                  inc(dfs,k);
                                  if dfs=flow then exit;
                             end;
                          p:=p^.next;
                     end;
               if d[s]=n then exit;
               dec(dv[d[x]]);
               if dv[d[x]]= then d[s]:=n;
               inc(d[x]);
               inc(dv[d[x]]);
          end;
 function trans(x:char):longint;inline;
          begin
               case x of
                    'A'..'Z':exit(ord(x)-ord('A')+);
                    'a'..'z':exit(ord(x)-ord('a')+);
               end;
          end;
 function getc:longint;inline;
          begin
               repeat
                     read(c1);
               until (upcase(c1)>='A') and (upcase(c1)<='Z');
               exit(trans(c1));
          end;
 begin
      readln(m);n:=;
      for i:= to n do a[i]:=nil;
      s:=;t:=;
      for i:= to m do
          begin
               j:=getc;k:=getc;readln(l);
               add(j,k,l);
          end;
      fillchar(d,sizeof(d),);
      fillchar(dv,sizeof(dv),);
      dv[]:=n;
      ans:=;
      while d[s]<n do inc(ans,dfs(s,maxlongint));
      writeln(ans);
 end.