What is wrong in this declaration of multidimensional array?

Asked May 29 '20 at 21:50

Active May 29 '20 at 21:50

Viewed 17 times

I have the following code:

dp = [[False]*n]*n
for i in range(n):
    dp[i][i] = True

But it will set all elements to true. For example, for n=2, I will get [[True, True], [True, True]] where I am expecting [[True, False], [False, True]]

Can anyone explain this?

asked May 29 '20 at 21:50

user3086871

2

@Makoto: No, there's a single loop over the diagonal. The problem is an aliasing issue. – user2357112 May 29 '20 at 21:55
Ah. I read it took quickly. I'll just sheepishly delete my comment... – Makoto May 29 '20 at 21:55
1

You didn't create a multidimensional array. Your outer list contains `n` references to the *same* inner list, not `n` different lists. – jasonharper May 29 '20 at 21:57

What is wrong in this declaration of multidimensional array?

0 Answers0