Happyleetcode42:intersection of Linked Lists

Write a program to find the node at which the intersection of the singly linked lists begins.

For example, the following, linked lists:

A:          a1→a2                                        c1→c2→c3                               B:     b1→b2→b3

Begin to intersect at node C1.

Notes:

• If The linked lists has no intersection at all, return null .
• The linked lists must retain their original structure after the function returns.
• You may assume there is no cycles anywhere in the entire linked structure.
• Your code should preferably run in O (n) time and use only O (1) memory.

Credits:
Special thanks to @stellari for adding this problem and creating all test cases.

Besides the difficulty of reading the subject, the problem is all right. A very good topic to do.

The code is as follows:

//* Definition for singly-linked list. structListNode {intVal; ListNode*Next; ListNode (intx): Val (x), Next (NULL) {}};classSolution { Public: ListNode*getintersectionnode (ListNode *heada, ListNode *headb) {        if(Heada = = NULL | | headb = =NULL)returnNULL; intLengtha=1, lengthb=1; ListNode*cora = Heada, *corb =headb;  while(Cora->next! =NULL) {Cora= cora->Next; Lengtha++; }         while(Corb->next! =NULL) {Corb= corb->Next; LENGTHB++; }        if(Cora->val! = corb->val)returnNULL; intdif = Lengtha-LENGTHB; Cora= Heada, Corb =headb; if(DIF >=0)        {             while(DIF) {dif--; Cora= cora->Next; }        }        Else

        {            while  (dif)            {                dif++                ; = Corb->next;            }        }          while (Cora! = NULL)        {            if (cora = = Corb                )return  Cora            ; Else             {                = cora->next;                 = Corb->Next;}}}    ;

Happyleetcode42:intersection of Linked Lists