test

var hasCycle = function (head) {
    while (head) {
        if (head.tag) return true
        head.tag = true
        head = head.next;
    }
    return false
};

var hasCycle = function (head) {
    let curr = head;
    while (curr) {
        if (curr.tag) return true
        curr.tag = true
        curr = curr.next;
    }
    return false
};