Insertion/Deletion of Doubly Linked List in constant time O(1)









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a) I have seen a lot of examples of this question in stackoverflow but I am still having problems understanding how does it know which node it is referring when call functions like insertAfter(Node n, Object o). If we say insert after node 2, how does linkedlist know which node is node 2?



b) in the previous posts in stackoverflow, it is said there is a pointer to a node that you want to insert after or before, that is why we get constant time operations. does that mean, just like we have to head and tail in linked list, we also have a pointer to each node?



would really appreciate help in understanding this.










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    up vote
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    down vote

    favorite












    a) I have seen a lot of examples of this question in stackoverflow but I am still having problems understanding how does it know which node it is referring when call functions like insertAfter(Node n, Object o). If we say insert after node 2, how does linkedlist know which node is node 2?



    b) in the previous posts in stackoverflow, it is said there is a pointer to a node that you want to insert after or before, that is why we get constant time operations. does that mean, just like we have to head and tail in linked list, we also have a pointer to each node?



    would really appreciate help in understanding this.










    share|improve this question

























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      a) I have seen a lot of examples of this question in stackoverflow but I am still having problems understanding how does it know which node it is referring when call functions like insertAfter(Node n, Object o). If we say insert after node 2, how does linkedlist know which node is node 2?



      b) in the previous posts in stackoverflow, it is said there is a pointer to a node that you want to insert after or before, that is why we get constant time operations. does that mean, just like we have to head and tail in linked list, we also have a pointer to each node?



      would really appreciate help in understanding this.










      share|improve this question















      a) I have seen a lot of examples of this question in stackoverflow but I am still having problems understanding how does it know which node it is referring when call functions like insertAfter(Node n, Object o). If we say insert after node 2, how does linkedlist know which node is node 2?



      b) in the previous posts in stackoverflow, it is said there is a pointer to a node that you want to insert after or before, that is why we get constant time operations. does that mean, just like we have to head and tail in linked list, we also have a pointer to each node?



      would really appreciate help in understanding this.







      list constants






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      edited Nov 11 at 7:18









      quant

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      1,53911526










      asked Sep 13 '12 at 5:47









      ueg1990

      3491930




      3491930






















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          If deletion is done using key then your point is valid because we dont know the position of the element to be deleted and thus finding key in the list makes its time linear in the length of the queue. But at places where it is written to be Constant time is deletion by address. So one may always move to that address and delete the node in constant time.



          Note : This ain't possible with singly linked list.






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          • why is it not possible?
            – dove
            Nov 27 '12 at 10:59










          • because in case of singly linked list you don't have location of parent to connect to next.
            – timedout
            Nov 28 '12 at 4:30










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          up vote
          2
          down vote













          If deletion is done using key then your point is valid because we dont know the position of the element to be deleted and thus finding key in the list makes its time linear in the length of the queue. But at places where it is written to be Constant time is deletion by address. So one may always move to that address and delete the node in constant time.



          Note : This ain't possible with singly linked list.






          share|improve this answer




















          • why is it not possible?
            – dove
            Nov 27 '12 at 10:59










          • because in case of singly linked list you don't have location of parent to connect to next.
            – timedout
            Nov 28 '12 at 4:30














          up vote
          2
          down vote













          If deletion is done using key then your point is valid because we dont know the position of the element to be deleted and thus finding key in the list makes its time linear in the length of the queue. But at places where it is written to be Constant time is deletion by address. So one may always move to that address and delete the node in constant time.



          Note : This ain't possible with singly linked list.






          share|improve this answer




















          • why is it not possible?
            – dove
            Nov 27 '12 at 10:59










          • because in case of singly linked list you don't have location of parent to connect to next.
            – timedout
            Nov 28 '12 at 4:30












          up vote
          2
          down vote










          up vote
          2
          down vote









          If deletion is done using key then your point is valid because we dont know the position of the element to be deleted and thus finding key in the list makes its time linear in the length of the queue. But at places where it is written to be Constant time is deletion by address. So one may always move to that address and delete the node in constant time.



          Note : This ain't possible with singly linked list.






          share|improve this answer












          If deletion is done using key then your point is valid because we dont know the position of the element to be deleted and thus finding key in the list makes its time linear in the length of the queue. But at places where it is written to be Constant time is deletion by address. So one may always move to that address and delete the node in constant time.



          Note : This ain't possible with singly linked list.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 27 '12 at 10:31









          timedout

          168210




          168210











          • why is it not possible?
            – dove
            Nov 27 '12 at 10:59










          • because in case of singly linked list you don't have location of parent to connect to next.
            – timedout
            Nov 28 '12 at 4:30
















          • why is it not possible?
            – dove
            Nov 27 '12 at 10:59










          • because in case of singly linked list you don't have location of parent to connect to next.
            – timedout
            Nov 28 '12 at 4:30















          why is it not possible?
          – dove
          Nov 27 '12 at 10:59




          why is it not possible?
          – dove
          Nov 27 '12 at 10:59












          because in case of singly linked list you don't have location of parent to connect to next.
          – timedout
          Nov 28 '12 at 4:30




          because in case of singly linked list you don't have location of parent to connect to next.
          – timedout
          Nov 28 '12 at 4:30

















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