Find maximum sum of sub-array of size k using sliding window technique

sliding_window_max_sum_of_sub_array_of_size_k.ts

function findMaxSumOfSequence(listOfItems: number[], sequenceLength: number) {
  if (listOfItems.length < sequenceLength) {
    return null;
  }
  let start = 0,
    end = 0,
    maxSum = 0,
    windowSum = 0;
  while (end < sequenceLength) {
    windowSum += listOfItems[end];
    end++;
    maxSum = windowSum;
  }
  while (start + sequenceLength < listOfItems.length) {
    windowSum = windowSum - listOfItems[start] + listOfItems[end];
    maxSum = Math.max(windowSum, maxSum);
    start++;
    end++;
  }

  return maxSum;
}

const input = [1, 2, 6, 2, 4, 1],
  windowSize = 3;

console.log(
  `Maximum sum of a sub-array of window size ${windowSize} is ${findMaxSumOfSequence(
    input,
    windowSize
  )}`
);