Grokking #207

class Solution {
  public int numSubarrayBoundedMax(int[] nums, int left, int right) {
    return atMost(nums, right) - atMost(nums, left - 1);
  }

  // count number of subarrays with max element less than or equal to "upper"
  public int atMost(int[] nums, int upper) {
    int ans = 0;

    int left = 0;
    for (int right = 0; right < nums.length; right++) {
      if (nums[right] > upper) {
        left = right + 1;
      }

      ans += right - left + 1;
    }

    return ans;
  }
}