#3392 - Count Subarrays of Length Three With a Condition

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Problem Description

Given an integer array nums, return the number of subarrays of length 3 such that the sum of the first and third numbers equals exactly half of the second number.

Solution

/**
 * @param {number[]} nums
 * @return {number}
 */
var countSubarrays = function(nums) {
  let count = 0;
  for (let i = 0; i < nums.length - 2; i++) {
    if (nums[i] + nums[i + 2] === nums[i + 1] / 2) {
      count++;
    }
  }
  return count;
};