S=“S1S2…Sn”是一个长为n的字符串，存放在一个数组中，编程序将S改造之后输出。S = "S1S2 ... Sn" is a string of length n, and stored in an array, output S after its programmable transformation. 1.将S的所有第偶数个字符按照其原来的下标从大到小的次序放在S的后半部分； 1.All the even-numbered characters of S should be placed in accordance with their subscript descending order in the second half of S;2.将S的所有第奇数个字符按照其原来的下标从小到大的次序放在S的前半部分；2.All the odd-numbered characters of S should be placed in accordance with their subscript ascending order in the first half of S.例如：S=‘ABCDEFGHIJKL’，则改造后的S为‘ACEGIKLJHFDB’。则 S=’algorithm’, 改造后为____________（Hint： 1. 答案不需要加引号 2. 系统基于字符匹配来判定答案，所以您的答案中不要出现空格）。For example: S = 'ABCDEFGHIJKL', then after the transformation S is 'ACEGIKLJHFDB'. If S = 'algorithm', then after the transformation S is ____________ (Hint:1. please don’t include any quotes in your answer. 2.This problem is judged by string matching, Please make sure your answer don't contain any blanks ).