Checking for looping in a singly linked list?

Question

Java

Tell me, please, where can I read intelligibly to a beginner on the algorithm for checking looping in a singly linked list?

Answer 1

en.wikipedia.org/wiki/Cycle_detection

Answer 2

var arr = [100, 1000, 10000, 30000];
var res = [];
arr.forEach((value, key) => {
  res.push((key
      ? (arr[key-1] + " - " + value)
      : ("< " + value)));

  if (key === (arr.length-1))
    res.push("> " + value);
});

console.log(res);