说明：  文本串加密和解密程序。一个文本串可用事先给定的字母映射表进行加密。 试写一个算法将输入的文本串进行加密后输出； 另写一个算法将输入的已加密的文本串进行解密后输出。
(Text string encryption and decryption process. Available in advance of a text string given letter mapping table is encrypted. For example, suppose the letter mapping table: abcdefgh I jklmnopqrstuvwxyz ngzqtcobmuhelkpdawxfy I vrsj the string " encrypt" is encrypted as " tkzwsdf" . Try to write an algorithm to input text string will be encrypted output another write encrypted text string entered an algorithm will be decrypted output.)