leetcode-334 递增的三元子序列

function increasingTriplet(nums) {
  let first = Infinity;
  let second = Infinity;
  for (const n of nums) {
    if (n <= first) {
      first = n;
    } else if (n <= second) {
      second = n;
    } else {
      return true;
    }
  }
  return false;
}