[vijos P1112] 小胖的奇偶

第一次看到这题怎么也不会想到是并查集题目…星期五第一次看到这题，到今天做出来，实在是废了好多功夫。看了很多人的解题都有same和diff数组，我也写了，后来发现不对啊两个数组的话find函数怎么写呢？hash也很久没写了，导致自己测试的时候有两个点没过是因为hash弄错了。

我的程序里f[x]= same[x] (x<=max)

= diff[x-max] (x>max)

总算，最后还是通过了。又是一道想不到思路就写不出的题。据说这题和食物链很像，那么食物链就是我的下一个目标~总感觉并查集是有点抽象的，我还没想到它怎么和树形结构具体联系起来。

BTW，vijos的数据挺弱的…

program vijos_p1112;
const BLOCK=;
var hash,f:array[..] of longint;
    n,m,i,a,b,t:longint;
    s:string;
function haha(x:longint):longint;
var t:longint;
begin
  t:=x mod ;
  while (hash[t]<>-) and (hash[t]<>x) do inc(t);
  exit(t);
end;

function find(x:longint):longint;
begin
  if f[x]=x then exit(x) else exit(find(f[x]));
end;

procedure union(x,y:longint);
var fx,fy:longint;
begin
  fx:=find(x);
  fy:=find(y);
  if fx<>fy then f[fx]:=fy;
end;

begin
  readln(n);
  readln(m);
  if m= then
    begin
      writeln();
      halt;
    end;
  for i:= to  do
    begin
      f[i]:=i;
      hash[i]:=-;
    end;
  for i:= to m do
    begin
      readln(s);
      t:=pos(' ',s);
      val(copy(s,,t-),a);
      delete(s,,t);
      t:=pos(' ',s);
      val(copy(s,,t-),b);
      delete(s,,t);
      if s='even' then
        begin
          if find(haha(a-))=find(haha(b+BLOCK)) then
            begin
              writeln(i-);
              halt;
            end
          else
            begin
              union(haha(a-),haha(b));
              union(haha(a-+BLOCK),haha(b+BLOCK));
            end;
        end
      else
        begin
          if find(haha(a-))=find(haha(b)) then
            begin
              writeln(i-);
              halt;
            end
          else
            begin
              union(haha(a-),haha(b+BLOCK));
              union(haha(a-+BLOCK),haha(b));
            end;
        end;
    end;
  writeln(m);
end.

小胖的奇偶

测试数据 #0: Accepted, time = 0 ms, mem = 1360 KiB, score = 10
测试数据 #1: Accepted, time = 0 ms, mem = 1360 KiB, score = 10
测试数据 #2: Accepted, time = 0 ms, mem = 1360 KiB, score = 10
测试数据 #3: Accepted, time = 0 ms, mem = 1364 KiB, score = 10
测试数据 #4: Accepted, time = 15 ms, mem = 1364 KiB, score = 10
测试数据 #5: Accepted, time = 15 ms, mem = 1360 KiB, score = 10
测试数据 #6: Accepted, time = 15 ms, mem = 1368 KiB, score = 10
测试数据 #7: Accepted, time = 0 ms, mem = 1364 KiB, score = 10
测试数据 #8: Accepted, time = 15 ms, mem = 1364 KiB, score = 10
测试数据 #9: Accepted, time = 0 ms, mem = 1364 KiB, score = 10

话说把奇怪的写失败了的东西也扔上来吧0 0

program vijos_p1112;
var same,diff:array[..] of integer;
    haha,f:array[..] of longint;
    n,m,i,j,a,b,t:longint;
    s:string;
function hash(x:longint):longint;
var t:longint;
begin
  t:=((x mod )*(x mod )) mod +;
  while (haha[t]<>) and (haha[t]<>x) do
    inc(t);
  haha[t]:=x;
  exit(t);
end;

{function find(x:longint):longint;   same &diff de find ya fen kai
begin
  if x=f[x] then exit(x) else exit(find(f[x]));
end; }

function sfind(x:longint):longint;
begin
  if hash(x)=same[hash(x)] then exit(hash(x)) else exit(sfind(same[hash(x)]));
end;

function dfind(x:longint):longint;
begin
  if hash(x)=diff[hash(x)] then exit(hash(x)) else exit(dfind(diff[hash(x)]));
end;

procedure union(x,y:longint;a,b:word);
var fx,fy:longint;
begin
  if a= then fx:=sfind(x) else fx:=dfind(x);
  if b= then fy:=sfind(y) else fy:=dfind(y);
  if (fx<>fy) then f[fx]:=fy;
end;

function pd:boolean;
var buzhidao:integer;
begin
  if s='even' then
    begin
      if sfind(same[hash(a-)])=dfind(diff[hash(b)]) then
        begin
          writeln(i-);
          halt;
        end;
    end
  else
    begin
      if sfind(same[hash(a-)])=sfind(same[hash(b)]) then
        begin
          writeln(i-);
          halt;
        end;
    end;
  pd:=true;
end;

begin
  readln(n);
  readln(m);
  for i:= to m* do
    begin
      same[i]:=i;
      diff[i]:=i+;
    end;
  for i:= to m do
    begin
      readln(s);
      t:=pos(' ',s);
      val(copy(s,,t-),a);
      delete(s,,t);
      t:=pos(' ',s);
      val(copy(s,,t-),b);
      delete(s,,t);
      if s='even' then
        begin
          if pd then
            begin
              union(same[hash(a-)],same[hash(b)],,);
              union(diff[hash(a-)],diff[hash(b)],,);
            end;
        end
      else
        begin
          if pd then
            begin
              union(same[hash(a-)],diff[hash(b)],,);
              union(diff[hash(a-)],same[hash(b)],,);
            end;
        end;
    end;
end.

小胖的奇偶-demo