Intersection of Two Linked Lists

https://leetcode.com/problems/intersection-of-two-linked-lists/

brute force:

start with link list 1 : check if that node is same as all other nodes of linklist 2;

traverse for all nodes of linklist 1

2nd solution :

use hash map

traverse and hash the address of the one linklist:

then for the second linklist if the address match any of the address of the hash , then that node is ans

3rd solution:

create 2 dummy node:

find the length of both the linklist

subtract the length of long -short

move the node of long by the subtracted ans

then traverse both the dummy node to find where the node matches

4th solution:

  class Solution {
public:
    ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
        if(headA==NULL  || headB==NULL) return NULL;
        ListNode *a=headA;
        ListNode *b=headB;
        while(a!=b){
            a= a==NULL? headB : a->next;
            b= b==NULL? headA : b->next;
        }
        return a;
    }
};