最长公共子序列

Posted 2020-12-27 brilliant107

肥肠神奇的方法  ：先把两个子序列‘合在一起’，再利用单调性求解。查找用二分

 1 var
 2 n,i,t,k:longint;
 3 a,b,c,q,id:array[0..100005]of longint;
 4 function find(l,r:longint):longint;
 5 var mid:longint;
 6 begin
 7  while l<r do
 8    begin
 9      mid:=(l+r) div 2;
10      if q[mid]>c[i] then r:=mid else l:=mid+1;
11    end;
12    exit(l);
13 end;
14 begin
15 readln(n);
16 for i:=1 to n do begin read(a[i]);id[a[i]]:=i;end;
17 for i:=1 to n do begin read(b[i]);c[i]:=id[b[i]];end;
18 for i:=1 to n do
19  begin
20   if q[t]<c[i] then begin inc(t); q[t]:=c[i]; end
21    else begin k:=find(0,t); q[k]:=c[i];end;
22  end;
23  writeln(t);
24 end.