We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  1. Linked Lists: Detect a Cycle
  2. Discussions

Linked Lists: Detect a Cycle

Sort 510 Discussions, By:

  • lukadias83
     + 0 comments

    C++

    bool has_cycle(Node* head) {
    // Complete this function
    // Do not write the main method
    
    Node* slowerPtr = head;
    Node* fasterPtr = head;
    
    if ( (head == nullptr) || (head->next == nullptr) ){
        return false;   
    }
    
    while( (fasterPtr != nullptr) && (fasterPtr->next != nullptr) ){
        slowerPtr = slowerPtr->next;
        fasterPtr = fasterPtr->next->next;
        if (slowerPtr == fasterPtr){
            return true;
        }
    }
    return false;
}

  • huseyinerensahin
     + 0 comments

    Cpp solution with O(n) complexity.

    bool has_cycle(Node* head) {
    map<Node*, int> ptrMap;
    Node *currPtr = head;
    while(currPtr != nullptr)
    {
        if(ptrMap.find(currPtr) != ptrMap.end())
        {
            return true;
        }
        ptrMap[currPtr]++;
        currPtr = currPtr->next;
    }
    return false;
}

  • EC1A_0310050
     + 0 comments

    bool has_cycle(Node* head) { Node *s=head,*f=head; while(s && f->next && f->next->next) { s=s->next; f=f->next->next; if(s==f) { return 1; } } return 0;

  • EC2A_0310068
     + 0 comments

    /* Detect a cycle in a linked list. Note that the head pointer may be 'NULL' if the list is empty.

    A Node is defined as: struct Node { int data; struct Node* next; } */

    bool has_cycle(Node* head) { // Complete this function // Do not write the main method if ( NULL == head ) return false;

    Node *temp = head;
Node **visit = new Node *[200];
int num=0;
while (temp )
{
    for (int i=0; i<num; i++)
    {
        if ( visit[i] == temp )
        {
            delete [] visit;
            return true;
        }
    }
    visit[num++] =temp;

        temp = temp->next;
}
return false;

    }

  • freemany
     + 0 comments

    Javascript:

    function checkCircle(nodes) {
    const preNodes = [];
    let node = nodes;
    do {
        preNodes.push(node);
        node = node.next;
       if (preNodes.some(n => n === node)) {
         return true;
       }
    } while (node !== null)
    
    return false;
}
Load more conversations