错误：
序列 b=[a1,a2,…,ai−1,ai+1,…,an−1,n]b=[a_1,a_2,\dots,a_{i-1},a_{i+1},\dots ,a_{n-1},n]b=[a1,a2,…,ai−1,ai+1,…,an−1,n]
应改为：
序列 b=[a1,a2,…,ai−1,ai+1,…,an−1,an]b=[a_1,a_2,\dots,a_{i-1},a_{i+1},\dots ,a_{n-1},a_n]b=[a1,a2,…,ai−1,ai+1,…,an−1,an]
b=[a_1,a_2,\dots,a_{i-1},a_{i+1},\dots ,a_{n-1},a_n]
