#795 - Number of Subarrays with Bounded Maximum

Medium • View on LeetCode • View on GitHub

Problem Description

Given an integer array nums and two integers left and right, return the number of contiguous non-empty subarrays such that the value of the maximum array element in that subarray is in the range [left, right].

The test cases are generated so that the answer will fit in a 32-bit integer.

Solution

/**
 * @param {number[]} nums
 * @param {number} left
 * @param {number} right
 * @return {number}
 */
var numSubarrayBoundedMax = function(nums, left, right) {
  let result = 0;
  let validCount = 0;
  let prevInvalidGreater = -1;

  for (let i = 0; i < nums.length; i++) {
    if (nums[i] > right) {
      validCount = 0;
      prevInvalidGreater = i;
    } else if (nums[i] >= left) {
      validCount = i - prevInvalidGreater;
    }

    result += validCount;
  }

  return result;
};