Bzoj 1207 打鼹鼠

题目：http://www.lydsy.com/JudgeOnline/problem.php?id=1207

一开始被这个二维平面吓到了。。没有想到可以用 f[i]表示打到第i只鼹鼠时最多打了几只

f[i]=max(f[i],f[j]+1),其中由j可以到i，即 0<=time[i]-time[j];

 

Code://欢迎大神指点

 

var

  n,m,i,j,ans:longint;

  f,x,y,time:array[0..10010]of longint;

function max(i,j:longint):longint;

begin

  if i>=j then exit(i);exit(j)

end;

procedure init;

var i:longint;

begin

  readln(n,m);

  fillchar(f,sizeof(f),0);

  for i:=1 to m do begin

    f[i]:=1;

    readln(time[i],x[i],y[i]);

  end;

  ans:=1;

end;

begin

  init;

  for i:=2 to m do

    for j:=1 to i-1 do

      if(f[j]+1>f[i])and(abs(x[i]-x[j])+abs(y[i]-y[j])<=time[i]-time[j])then

        f[i]:=f[j]+1;

  for i:=1 to m do ans:=max(ans,f[i]);

  writeln(ans)

end.