SDE - 1

Given an array “arr” of “N” integers. Your task is to find and return all the indices of local minima and local maxima in the given array. You need to return the indices in a 2-D list where the first(0th) row denotes the indices of local minima and the second row denotes the indices of local maxima. In case if there is no local minima or maxima return -1 as the only row element.

We say that an array element arr[i] is a local minimum if it is less than to its neighbours, and local maximum if it is greater than to its neighbours.

Note:

For corner elements, we need to consider only one neighbour for comparison.    

For Example:

For the given array :  10 5 20 30 40 35 50

The red circle at index 1,5 are local minima because elements at index 1, and 5 both are smaller to its neighbours.

The green circle at index 0,4,6 are local maxima, because element at index 4 is greater than its neighbours, and element at 0, and 4 are corner elements and also greater than its one neighbour.