bzoj 1934: [Shoi2007]Vote 善意的投票 （最小割）

原来是赞同的连源，原来是反对的连汇，然后是朋友的就连在一起，这样最小割就是割掉违背和谐的吧

type
  arr=record
    toward,next,cap:longint;
  end;
const
  maxm=;
  maxn=;
var
  first,col,gap,d,cur:array[..maxn]of longint;
  edge:array[..maxm]of arr;
  esum,tot,s,t,n:longint;

function min(x,y:longint):longint;
begin
  if x<y then exit(x);
  exit(y);
end;

procedure add(j,k,l:longint);
begin
  inc(esum);
  edge[esum].toward:=k;
  edge[esum].next:=first[j];
  first[j]:=esum;
  edge[esum].cap:=l;
end;

procedure addedge(j,k,l:longint);
begin
  add(j,k,l);
  add(k,j,);
end;

procedure into;
var
  i,j,n,m:longint;
begin
  readln(n,m);
  fillchar(first,sizeof(first),);
  esum:=-;
  tot:=n+;
  s:=n+;
  t:=n+;
  for i:= to n do begin
    read(col[i]);
    if col[i]= then addedge(s,i,)
      else addedge(i,t,);
  end;
  while m> do begin
    dec(m);
    read(i,j);
    if col[i]= then addedge(i,j,)
      else addedge(j,i,);
  end;
end;

function sap(x,flow:longint):longint;
var
  now,more,too,i:longint;
begin
  if x=t then exit(flow);
  i:=cur[x];
  now:=;
  while i>= do begin
    too:=edge[i].toward;
    if (d[x]=d[too]+) and (edge[i].cap>) then begin
      more:=sap(too,min(edge[i].cap,flow-now));
      dec(edge[i].cap,more);
      inc(edge[i xor ].cap,more);
      inc(now,more);
      cur[x]:=i;
      if now=flow then exit(flow);
    end;
    i:=edge[i].next;
  end;
  dec(gap[d[x]]);
  if gap[d[x]]= then d[s]:=tot;
  inc(d[x]);
  inc(gap[d[x]]);
  cur[x]:=first[x];
  exit(now);
end;

function maxflow:longint;
var
  i,ans:longint;
begin
  fillchar(d,sizeof(d),);
  fillchar(gap,sizeof(gap),);
  gap[]:=tot;
  for i:= to n do cur[i]:=first[i];
  ans:=;
  while d[s]<tot do inc(ans,sap(s,maxlongint));
  exit(ans);
end;

begin
  into;
  writeln(maxflow);
end.