PAT1050 String Subtraction (20分) 用布尔数组

Given two strings S​1​​ and S​2​​ , S=S​1​​ −S​2​​ is defined to be the remaining string after taking all the characters in S​2​​ from S​1​​ . Your task is simply to calculate S1​​​ −S​2​​ for any given strings.

PAT 1035 Password (20分) 字符替换

To prepare for PAT, the judge sometimes has to generate random passwords for the users. The problem is that there are always some confusing passwords since it is hard to distinguish 1 (one) from l (L in lowercase), or 0 (zero) from O (o in uppercase).