考虑大小写和非字母字符的代码：letter_list = [chr(ord('a') + i) for i in range(26)] new_list = [] while True: try: key = input().lower() s = input() for i in key: if i not in new_list: new_list.append(i) for j in letter_list: if j not in new_list: new_list.append(j) m = dict(zip(letter_list, new_list)) code = [] for item in s: if not item.isalpha(): code.append(item) elif item.isupper(): code.append(m[item.lower()].upper()) else: code.append(m[item]) print("".join(code)) except: break