1562: [NOI2009]变换序列

Description

Input

Output

Sample Input

5

1 1 2 2 1

Sample Output

1 2 4 0 3

HINT

30%的数据中N≤50；
60%的数据中N≤500；
100%的数据中N≤10000。

二分图匹配，倒着匹配，每次选小的增广（随便乱yy一下，应该就可以证明是字典序最小的吧）

const
    maxn=10010;
var
    first,link:array[0..maxn]of longint;
    a:array[0..maxn,0..1]of longint;
    next,last:array[0..maxn]of longint;
    n:longint;

procedure swap(var x,y:longint);
var
    t:longint;
begin
    t:=x;x:=y;y:=t;
end;

procedure init;
var
    i,x:longint;
begin
    read(n);
    for i:=1 to n do
      begin
        read(x);
        a[i,0]:=i+x;
        a[i,1]:=i-x;
        if a[i,0]>n then dec(a[i,0],n);
        if a[i,1]<1 then inc(a[i,1],n);
        if a[i,0]>a[i,1] then swap(a[i,0],a[i,1]);
      end;
end;

var
    time:longint;
    flag:array[0..maxn]of longint;

function path(x:longint):boolean;
var
    i:longint;
begin
    for i:=0 to 1 do
      if (i=0) or (a[x,i]<>a[x,i-1]) then
        if flag[a[x,i]]<>time then
        begin
          flag[a[x,i]]:=time;
          if (link[a[x,i]]=0) or (path(link[a[x,i]])) then
          begin
            link[a[x,i]]:=x;
            exit(true);
          end;
        end;
    exit(false);
end;

procedure work;
var
    i:longint;
begin
    for i:=n downto 1 do
      begin
        inc(time);
        if path(i)=false then
        begin
          writeln('No Answer');
          exit;
        end;
      end;
    for i:=1 to n do
      if link[a[i,0]]=i then write(a[i,0]-1,' ')
      else write(a[i,1]-1,' ');
end;

begin
    init;
    work;
end.