intersectionOfLists.java

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

// For example, the following two linked lists:


// begin to intersect at node c1.

 

// Example 1:


// Input: intersectVal = 8, listA = [4,1,8,4,5], listB = [5,0,1,8,4,5], skipA = 2, skipB = 3
// Output: Reference of the node with value = 8
// Input Explanation: The intersected node's value is 8 (note that this must not be 0 if the two lists intersect). From the head of A, it reads as [4,1,8,4,5]. From the head of B, it reads as [5,0,1,8,4,5]. There are 2 nodes before the intersected node in A; There are 3 nodes before the intersected node in B.
 

// Example 2:


// Input: intersectVal = 2, listA = [0,9,1,2,4], listB = [3,2,4], skipA = 3, skipB = 1
// Output: Reference of the node with value = 2
// Input Explanation: The intersected node's value is 2 (note that this must not be 0 if the two lists intersect). From the head of A, it reads as [0,9,1,2,4]. From the head of B, it reads as [3,2,4]. There are 3 nodes before the intersected node in A; There are 1 node before the intersected node in B.
 

// Example 3:


// Input: intersectVal = 0, listA = [2,6,4], listB = [1,5], skipA = 3, skipB = 2
// Output: null
// Input Explanation: From the head of A, it reads as [2,6,4]. From the head of B, it reads as [1,5]. Since the two lists do not intersect, intersectVal must be 0, while skipA and skipB can be arbitrary values.
// Explanation: The two lists do not intersect, so return null.


/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */


public class Solution {
    public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
        List<ListNode> list = new ArrayList<ListNode>();
        ListNode tempA = headA;
        ListNode tempB = headB;
        ListNode intersect = null;
        while(tempA != null){
            list.add(tempA);
            tempA = tempA.next;
        }
        
        while(tempB != null){
            if(list.contains(tempB)){
                intersect = tempB;
                return intersect;
            }
            tempB = tempB.next;
        }
    return null;}
}