ex2.dpr

tongji acm-online judge solution

{
the same to "ex1.dpr"
}
program Ural_1223(Input,Output);
const
	MaxN=1000;
	MaxM=10; //Log(MaxN)
	MaxValue=MaxLongint;
type
	TIndex=Longint;
	TDP=array[0..1]of array[0..MaxN]of TIndex;
var
	N,M:TIndex;
	F:TDP;

function Log2(x:TIndex):TIndex;
begin
	Result:=Trunc(Ln(x)/Ln(2));
	while 1 shl Result<x do Inc(Result);
end;
function Max(A,B:TIndex):TIndex;
begin
	if A>B then Result:=A
	else Result:=B;
end;
function GetValue(Line,i,j:TIndex):TIndex;
begin
	if 1 shl i>=j+1 then Result:=Log2(j+1)
	else Result:=F[Line][j];
end;
procedure Main;
var
	i,j,k:TIndex;
	Tmp:TIndex;
	Now,Old:TIndex;
begin
	while true do
	begin
		Read(M);
		if M=0 then Break;
		Readln(N);
		if M>=MaxM then
		begin
			Writeln(Log2(N+1));
			Continue;
		end;
		if 1 shl M>=N+1 then
		begin
			Writeln(Log2(N+1));
			Continue;
		end;
		FillChar(F,SizeOf(F),0);
		Now:=0;
		for j:=0 to N do 
			F[Now][j]:=j;
		for i:=2 to M do
		begin
			Old:=Now;
			Now:=1-Now;
			for j:=1 shl i to N do // when m>=ceil(log(n+1)), f(n,m) can be directly got.
			begin
				F[Now][j]:=MaxValue;
				for k:=1 to j do
				begin
					Tmp:=Max(GetValue(Old,i-1,k-1),GetValue(Now,i,j-k))+1;
					if Tmp<F[Now][j] then F[Now][j]:=Tmp;
				end;
			end;
		end;
		Writeln(F[Now][N]);
	end;
end;
begin
{$IFNDEF ONLINE_JUDGE}
	Assign(Input,'i.txt');
	Reset(Input);
	Assign(Output,'o.txt');
	Rewrite(Output);
{$ENDIF}
	Main;
{$IFNDEF ONLINE_JUDGE}
	Close(Input);
	Close(Output);
{$ENDIF}
end.