https://practice.geeksforgeeks.org/problems/stock-span-problem/0

stock-span-problem.js

// https://practice.geeksforgeeks.org/problems/stock-span-problem/0
function stockSpan(arr) {
  let idx;
  let len = arr.length;
  let resArr = new Array(arr.length);
  // It's always 1 because nothing is before this.
  resArr[0] = 1;
  for (idx = 1; idx < len; idx++) {
    resArr[idx] = 1;
    // Traverse left while the next element on left is smaller
    let idxJ = idx - 1;
    while (idxJ >= 0 && arr[idx] >= arr[idxJ]) {
      // idxJ goes to left
      resArr[idx] += 1;
      idxJ -= 1;
    }
  }
  return resArr;
}

const arrEx1 = [100, 80, 60, 70, 60, 75, 85];
const resEx1 = stockSpan(arrEx1);
console.log(resEx1.join(',') === '1,1,1,2,1,4,6');

const arrEx2 = [10, 4, 5, 90, 120, 80];
const resEx2 = stockSpan(arrEx2);
console.log(resEx2.join(',') === '1,1,2,4,5,1');