1.
a=[]
arrays=[a*3]
In fact, as arrays[[]]
2.
arrays=[a]*N
It appears to be to create a two-dimensional array, but only creates N pointing to a reference, so once a change, arrays in the N list will change
eg:
a=[]
N=3
arrays=[a]*3
arrays[0].append(1)#看上去只为第一个list添加整数1,实际上---
print(arrays)
Output[[1], [1], [1]]
3.
arrays=[[]for i in range(N)]
eg:
N=3
arrays=[[]for i in range(N)]
print(arrays)
Output[[], [], []]