c++algorithmarrays

how to swap array-elements to transfer the array from a column-like into a row-like representation

For example: the array

a1, a2, a3, b1, b2, b3, c1, c2, c3, d1, d2, d3

represents following table

a1, b1, c1, d1
a2, b2, c2, d2
a3, b3, c3, d3

now i like to bring the array into following form

a1, b1, c1, d1, a2, b2, c2, d2, a3, b3, c3, d3

Does an algorithm exist, which takes the array (from the first form) and the dimensions of the table as input arguments and which transfers the array into the second form? I thougt of an algorithm which doesn't need to allocate additional memory, instead i think it should be possible to do the job with element-swap operations.

Solution

  • The term you're looking for is in-place matrix transpose, and here's an implementation.