【NOIP2017练习】函数变换（DP，dfs）

题意：

思路：

极限步数大概不会超过30

const max=100000;
var dp:array[1..max,0..2]of longint;
    eul:array[1..max]of longint;
    cas,v,n,k,i,ans,j:longint;

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

function euler(x:longint):longint;
var tmp,i:longint;
begin
 if x<=max then exit(eul[x]);
 euler:=x; tmp:=trunc(sqrt(x));
 for i:=2 to tmp do
  if x mod i=0 then
  begin
   while x mod i=0 do x:=x div i;
   euler:=euler div i*(i-1);
  end;
 if x>1 then euler:=euler div x*(x-1);
end;

function clac(n,k:longint):longint;
begin
 if n<=max then exit(dp[n,k]);
 clac:=clac(euler(n),k)+1;
 if k>0 then clac:=min(clac,clac((n>>1)+1,k-1)+1);
end;

begin
 assign(input,'func.in'); reset(input);
 assign(output,'func.out'); rewrite(output);
 readln(cas);
 for i:=1 to max do eul[i]:=i;
 for i:=2 to max do
 begin
  if eul[i]=i then
   for j:=1 to max div i do eul[i*j]:=eul[i*j] div i*(i-1);
  dp[i,0]:=dp[eul[i],0]+1;
  dp[i,1]:=min(dp[eul[i],1],dp[(i>>1)+1,0])+1;
  dp[i,2]:=min(dp[eul[i],2],dp[(i>>1)+1,1])+1;
 end;

 for v:=1 to cas do
 begin
  readln(n,k);
  ans:=clac(n,0);
  if k>0 then ans:=min(ans,clac(n,1));
  if k>1 then ans:=min(ans,clac(n,2));
  writeln(ans);
 end;
 close(input);
 close(output);
end.