CH Round #51 - Shinrein祭 #1

A.Phorni

题目：http://www.contesthunter.org/contest/CH%20Round%20%2351%20-%20Shinrein祭%20%231/Phorni

没做。。。

B.Arietta

题目：http://www.contesthunter.org/contest/CH%20Round%20%2351%20-%20Shinrein祭%20%231/Arietta

想到了网络流，所以每次暴力算出哪些点能被弹奏，就从这次弹奏向哪些点连容量为1的边

最后由s向所有力度连容量为该力度最多能被弹多少次的边，由每个节点连t容量为1的边

求最大流，得到了暴力分30分。正解还不会

代码：

  1 const inf=maxlongint;maxn=10000+100;maxm=1000000;
  2 type node=record
  3      go,next,v:longint;
  4      end;
  5 var  tot,i,n,m,maxflow,l,r,s,t,x,y,tot2:longint;
  6      h,head,head2,q,cur,v:array[0..maxn] of longint;
  7      e:array[0..maxm] of node;
  8      e2:array[0..maxn] of node;
  9      function min(x,y:longint):longint;
 10       begin
 11       if x<y then exit(x) else exit(y);
 12       end;
 13 procedure ins(x,y,z:longint);
 14  begin
 15  inc(tot);
 16  e[tot].go:=y;e[tot].v:=z;e[tot].next:=head[x];head[x]:=tot;
 17  end;
 18 procedure insert(x,y,z:longint);
 19  begin
 20  ins(x,y,z);ins(y,x,0);
 21  end;
 22 function bfs:boolean;
 23  var i,x,y:longint;
 24  begin
 25  fillchar(h,sizeof(h),0);
 26  l:=0;r:=1;q[1]:=s;h[s]:=1;
 27  while l<r do
 28   begin
 29   inc(l);
 30   x:=q[l];
 31   i:=head[x];
 32   while i<>0 do
 33    begin
 34    y:=e[i].go;
 35    if (e[i].v<>0) and (h[y]=0) then
 36     begin
 37      h[y]:=h[x]+1;
 38      inc(r);q[r]:=y;
 39     end;
 40    i:=e[i].next;
 41    end;
 42   end;
 43  exit (h[t]<>0);
 44  end;
 45 function dfs(x,f:longint):longint;
 46  var i,y,used,tmp:longint;
 47  begin
 48  if x=t then exit(f);
 49  used:=0;
 50  i:=cur[x];
 51  while i<>0 do
 52   begin
 53   y:=e[i].go;
 54   if (h[y]=h[x]+1) and (e[i].v<>0) then
 55    begin
 56    tmp:=dfs(y,min(e[i].v,f-used));
 57    dec(e[i].v,tmp);if e[i].v<>0 then cur[x]:=i;
 58    inc(e[i xor 1].v,tmp);
 59    inc(used,tmp);
 60    if used=f then exit(f);
 61    end;
 62   i:=e[i].next;
 63   end;
 64  if used=0 then h[x]:=-1;
 65  exit(used);
 66  end;
 67 procedure dinic;
 68  var i:longint;
 69  begin
 70  while bfs do
 71   begin
 72   for i:=s to t do cur[i]:=head[i];
 73   inc(maxflow,dfs(s,inf));
 74   end;
 75  end;
 76 procedure insert2(x,y:longint);
 77  begin
 78  inc(tot2);
 79  e2[tot2].go:=y;e2[tot2].next:=head2[x];head2[x]:=tot2;
 80  end;
 81 procedure init;
 82  begin
 83    tot:=1;
 84    readln(n,m);
 85    for i:=2 to n do begin read(x);insert2(x,i);end;readln;
 86    for i:=1 to n do read(v[i]);readln;
 87  end;
 88 procedure dfss(x:longint);
 89  var j,y:longint;
 90  begin
 91  if (v[x]>=l) and (v[x]<=r) then insert(i,x,1);
 92  j:=head2[x];
 93  while j<>0 do
 94   begin
 95     y:=e2[j].go;
 96     dfss(y);
 97     j:=e2[j].next;
 98   end;
 99  end;
100 
101 procedure main;
102  begin
103    s:=0;t:=n+m+1;
104    for i:=1 to n do insert(i,t,1);
105    for i:=n+1 to n+m do
106     begin
107       readln(l,r,x,y);
108       insert(s,i,y);
109       dfss(x);
110     end;
111    maxflow:=0;
112    dinic;
113    writeln(maxflow);
114  end;
115 
116 begin
117   init;
118   main;
119 end.                       

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