encode.pas

来自「PASCAL光盘资料PASCAL光盘资料PASCAL光盘资料」· PAS 代码 · 共 38 行

program encode(input,output);
var  word:string[7];
     i,j,len,ans:longint;

function c(n:longint;r:longint):longint;  {计算Cr n}
var  i,cc:longint;
begin
    cc:=1;
    for i:=1 to r do
      cc:=cc*(n+1-i) div i;
    c:=cc;
end;

begin  {main}
  assign(input,'encode.in');
  assign(output,'encode.out');
  reset(input);
  rewrite(output);
  readln(word);   {读入串}
  word:=pred('a')+word;
  len:=length(word)-1;
  ans:=1;
  for i:=2 to len do   {加上长为1-（len-1）所有串后编码}
      ans:=ans+c(26,i-1);
  for i:=2 to len+1 do
      if (word[i]>word[i-1]) then
         for j:=ord(word[i-1])+1 to ord(word[i])-1 do  {第i个位置为这么多字母时，编号比其小，要加上情况数}
             ans:=ans+c(26-j+ord(word[1]),len-i+1)
      else
      begin
           ans:=0;
           break;
      end;
  writeln(ans);   {输出}
  close(input);
  close(output);
end.