自行设计随机生成n=30的S串；实现删除子串算法Deletestr（sqstr s，sqstr sub）；分析T（n）；讨论s=’aaa….abbb….b’，sub=’ab’的执行结果。-Design their own randomly generated n = 30 S-string Delete the substring the algorithm Deletestr (sqstr s, sqstr sub) analysis of T (n) discussion s =