sawtooth

#include <iostream>
#include <vector>

int sawtooth(const std::vector<int> &nums);
bool satisfySawToothPredicate(const std::vector<int> &nums, int idx);

int main()
{
   std::vector<int> nums1{9, 8, 7, 6};
   std::vector<int> nums2{1, 2, 3, 4};
   std::vector<int> nums3{1, 2, 1};
   std::vector<int> nums4{1, 2, 1, 1, 1, 2, 1};
   std::vector<int> nums5{1, 1, 1, 1, 1, 1};
   std::cout << "sawtooth(nums1) = " << sawtooth(nums1) << std::endl;
   std::cout << "sawtooth(nums2) = " << sawtooth(nums2) << std::endl;
   std::cout << "sawtooth(nums3) = " << sawtooth(nums3) << std::endl;
   std::cout << "sawtooth(nums4) = " << sawtooth(nums4) << std::endl;
   std::cout << "sawtooth(nums5) = " << sawtooth(nums5) << std::endl;
}

int sawtooth(const std::vector<int> &nums)
{
   int left, right, size;
   int amountOfSubArraysWhichAreSawTooths;

   size = nums.size();
   left = right = 0;
   amountOfSubArraysWhichAreSawTooths = 0;

   for (right = 1; right < size; ++right)
   {
      if ((right - left <= 1 && nums[right] != nums[left]) ||
          (right - left > 1 && satisfySawToothPredicate(nums, right)))
      {
         amountOfSubArraysWhichAreSawTooths = amountOfSubArraysWhichAreSawTooths + right - left;
      }
      else
      {
         left = (left + 1 == right ? right : --right);
      }
   }
   return amountOfSubArraysWhichAreSawTooths;
}

bool satisfySawToothPredicate(const std::vector<int> &nums, int idx)
{

   return (nums[idx] - nums[idx - 1]) * (nums[idx - 1] - nums[idx - 2]) < 0;
}