Topic
Idea
C++ solution. Use slow and fast pointer, during the traversal, slow pointer takes one step and fast takes two steps. If there is a cycle in the list, the fast pointer will equal to slow pointer. Otherwise, fast pointer will reach the tail first.
C++ Solution
bool has_cycle(Node* head) {
if(head == NULL || head->next == NULL){
return false;
}
Node* slow = head;
Node* fast = head->next;
while(slow != fast){
if(fast == NULL || fast->next == NULL) return false;
slow = slow->next;
fast = fast->next->next;
}
return true;
}
