[Leetcode] 160. Intersection of the Linked Lists problem solving ideas

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.

Question: Determine if two lists have intersecting elements, and if so, find the Intersect node.

This problem is also a basic problem, to see their list of knowledge needs to be consolidated under the good.

Find out the length of the two lists separately len1, Len2, and their length difference diff

Skip the length Difference section, for the remainder of the same length section, check the corresponding nodes of two linked lists, if there are intersecting nodes, there must be two corresponding nodes equal.

1ListNode *getintersectionnode (ListNode *heada, ListNode *headb) {2         3         intLen1 =0;4listnode* P1 =Heada;5          while(P1! =NULL) {6P1 = p1->Next;7len1++;8         }9         Ten         intLen2 =0; Onelistnode* P2 =headb; A          while(P2! =NULL) { -P2 = p2->Next; -len2++; the         } -          -P1 =Heada; -P2 =headb; +         if(Len1 >len2) { -             intdiff = len1-Len2; +              while(diff >0){ AP1 = p1->Next; atdiff--; -             } -         } -          -         if(Len2 >len1) { -             intdiff = len2-len1; in              while(diff >0){ -P2 = p2->Next; todiff--; +             } -         } the          *          while(P1! =NULL) { $             if(P1 = =p2) {Panax Notoginseng                 returnP1; -             } theP1 = p1->Next; +P2 = p2->Next; A         } the          +         returnNULL; -}

Resources:

Leetcode:intersection of the Linked Lists problem solving report, Yu ' s garden

[Leetcode] 160. Intersection of the Linked Lists problem solving ideas