Redo the palindrome problem (Lec 4-2 ) using recursion. You cannot use the old version, otherwise not only will you get no credits for this lecture, we will take PENALTY points.
重做 Lec 4-2 palindrome 那一題，請用“遞迴函式”的方法，否則不但不算分還會被倒扣分數！
abcba
a palindrome