Question

Given below an example of Singly linked list which contains loop

node_1 –> node_2 –> node_3 –> node_4 –> node_5 –> node_3

i want to detect whether loop exists or not for any given linked list by taking performance factor into consideration .

Answer 1

function boolean hasLoop(Node startNode){
      Node slowNode = Node fastNode = startNode;
      while(true){
          if(slowNode)
             return false;
          else if(((slowNode==fastNode)&&fastNode!=startNode)||fastNode->next==slowNode)
              return true;
          else{
              slowNode=slowNode->next;
              fastNode=fastNode->next->next;
          }
      }
    }