longest-subs.js

// Task: Given an array of N numbers. 
// Find longest subsequence of increasing numbers

let findLongestSubs = function(arr) {
  if (arr.length === 0) {
    return null;
  } else if (arr.length === 1) {
    return arr[0];
  } else {
    let longestLen = 1;
    let resL = l = 0, resR = r = 1;
    for(let i=1; i<arr.length; ++i) {
      if (arr[i] > arr[i-1]) {
        r = i;
      } else {
        l = i;
      }
      if (r-l > longestLen) {
        longestLen = r-l
        resL = l;
        resR = r;
      }
    }
    return arr.slice(resL, resR+1)
  }
}

let arr = [-1, 1, 2, 3, 7, 8, 9, 14, 5, 6, 8, 9, 10, 11, 12]
console.log(findLongestSubs(arr)) // [-1, 1, 2, 3, 7, 8, 9, 14]