Changing direction

Changing direction

Simple

You are given a sequence of integers. Your task in this mission is to find, how many times the sorting direction was changed in the given sequence. If the elements are equal - the previous sorting direction remains the same, if the sequence starts from the same elements - look for the next different to determine the sorting direction.

Let's look at the scheme:

changing_dir

There are three sorting directions:

  • on the chunk 1, 2, 2 - up (increasing);
  • on the chunk 2, 1 - down (decreasing);
  • and on the chunk 1, 2, 2 - up again.
So, you have two points of changing the sorting direction: #1 - from up to down, and #2 - from down to up. That's the result your function should return.

Input: List of integers (int).

Output: An integer (int).

Examples: 

assert changing_direction([1, 2, 3, 4, 5]) == 0
assert changing_direction([1, 2, 3, 2, 1]) == 1
assert changing_direction([1, 2, 2, 1, 2, 2]) == 2

Preconditions:

  • the sequence is non-empty;
  • the elements are positive integers.

18
Doppelok
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