[SOLVED]Explain this output

Question

I found this question in cpp challenge.
I can't understand how answer is 3
Anyone explain pleasehttps://www.sololearn.com/post/109492/?ref=app

Answer 1

This is a multi dimensional array as you know. But what you are cofused is about "0[1[arr]]" to understand this you need to know that : arr[i] = *(arr+i) = *(i+arr) = i[arr]
In the question above 0[1[arr]]={(1,2),(3,5)}.
Step1 : 1[arr] selects the second row of array.
Step2 : 0[1[arr]] selects the first element of second row.