bzoj 1207: [HNOI2004]打鼹鼠 （dp）

var
n,m,i,j,ans:longint;
x,y,time,f:array[0..10010]of longint;

begin
readln(n,m);
for i:=1 to m do

readln(time[i],x[i],y[i]);
ans:=1;
for i:=1 to m do begin
f[i]:=1;
for j:=1 to i-1 do
if (time[i]-time[j]>=abs(x[i]-x[j])+abs(y[i]-y[j])) and (f[i]<f[j]+1) then begin
f[i]:=f[j]+1;
if f[i]>ans then ans:=f[i];
end;
end;
writeln(ans);
end.