1562: [NOI2009]变换序列 - BZOJ

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=;
 var
     first,link:array[..maxn]of longint;
     a:array[..maxn,..]of longint;
     next,last:array[..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:= to n do
       begin
         read(x);
         a[i,]:=i+x;
         a[i,]:=i-x;
         if a[i,]>n then dec(a[i,],n);
         if a[i,]< then inc(a[i,],n);
         if a[i,]>a[i,] then swap(a[i,],a[i,]);
       end;
 end;

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

 function path(x:longint):boolean;
 var
     i:longint;
 begin
     for i:= to  do
       if (i=) or (a[x,i]<>a[x,i-]) then
         if flag[a[x,i]]<>time then
         begin
           flag[a[x,i]]:=time;
           if (link[a[x,i]]=) 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  do
       begin
         inc(time);
         if path(i)=false then
         begin
           writeln('No Answer');
           exit;
         end;
       end;
     for i:= to n do
       if link[a[i,]]=i then write(a[i,]-,' ')
       else write(a[i,]-,' ');
 end;

 begin
     init;
     work;
 end.