打印文字练习。随机产生要录入的字符串，且该串不能出现连续重复的字符。用户输入录入个数，计算用户录入文字耗时。 程序清晰，你值得拥有！-Print writing practice. Random input string, the string and not consecutive repeating characters. Input from the user input the number, calculate the user input text time-consuming.