multi-dimensional array vs pointers

Question

int a[3][2] = {{3,6}, {8,4}, {7,1}};
cout << *a[1] << *(*a+1);

// outputs 86

Three rows and two columns.
Does a[1] imply a[1][0]?

How does *(*a+1) give a[0][1] ?
I do not know how pointers are used in this case.

Answer 1

Multidimensional arrays are stored linear just as normal arrays. So your 2D array looks like this in memory:
int a[6] = {3, 6, 8, 4, 7, 1};
The compiler however knows how to handle the array. a[1] returns the address to the second block of the outer array, so it points to the 8. *(*a+1) however increments the starting address of the array by one so it points to 6.

It might seem a bit weird and it is in some way so I recommend to always use the full address of the element you want to select. So I'd write
&a[1][0]
instead of
a[1]
because it more clear.