UNIX入門課程1061_ex8

http://erdos.csie.ncnu.edu.tw/~klim/unix-intro/unix-intro-1061.html

作業八: hanoi tower
•建立一個 shell 執行檔, 名為 hanoi, 可印出 hanoi tower problem 中 disc 移動的順序

$ ./hanoi 2    # move 2 discs, from A to B by C
from A to C
from A to B
from C to B
$ ./hanoi 3    # move 3 discs, from A to B by C
from A to B
from A to C
from B to C
from A to B
from C to A
from C to B
from A to B
$

解答:

#!/bin/bash
function move_disc {
  if [ $1 -ne 0 ]; then
    move_disc $(($1-1)) $2 $4 $3
      echo from $2 "to" $3
    move_disc $(($1-1)) $4 $3 $2
  fi
}
#-----Main Program-----
disc=$1
if [ $disc -gt 0 ]; then
  move_disc $disc A B C
fi

執行結果: