Algorithm
Problem Name: 160. Intersection of Two Linked Lists
The test cases are generated such that there are no cycles anywhere in the entire linked structure.
Note that the linked lists must retain their original structure after the function returns.
Custom Judge:
The inputs to the judge are given as follows (your program is not given these inputs):
intersectVal- The value of the node where the intersection occurs. This is0if there is no intersected node.listA- The first linked list.listB- The second linked list.skipA- The number of nodes to skip ahead inlistA(starting from the head) to get to the intersected node.skipB- The number of nodes to skip ahead inlistB(starting from the head) to get to the intersected node.
The judge will then create the linked structure based on these inputs and pass the two heads, headA and headB to your program. If you correctly return the intersected node, then your solution will be accepted.
Example 1:
Input: intersectVal = 8, listA = [4,1,8,4,5], listB = [5,6,1,8,4,5], skipA = 2, skipB = 3 Output: Intersected at '8' 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 [5,6,1,8,4,5]. There are 2 nodes before the intersected node in A; There are 3 nodes before the intersected node in B. - Note that the intersected node's value is not 1 because the nodes with value 1 in A and B (2nd node in A and 3rd node in B) are different node references. In other words, they point to two different locations in memory, while the nodes with value 8 in A and B (3rd node in A and 4th node in B) point to the same location in memory.
Example 2:
Input: intersectVal = 2, listA = [1,9,1,2,4], listB = [3,2,4], skipA = 3, skipB = 1 Output: Intersected at '2' 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 [1,9,1,2,4]. 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: No intersection 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.
Constraints:
- The number of nodes of
listAis in them. - The number of nodes of
listBis in then. 1 <= m, n <= 3 * 1041 <= Node.val <= 1050 <= skipA < m0 <= skipB < nintersectValis0iflistAandlistBdo not intersect.intersectVal == listA[skipA] == listB[skipB]iflistAandlistBintersect.
Code Examples
#1 Code Example with C Programming
Code -
C Programming
struct ListNode *getIntersectionNode(struct ListNode *headA, struct ListNode *headB) {
struct ListNode *a = headA, *b = headB;
if (!a || !b) return NULL;
while (a != b) {
a = a ? a->next : headB;
b = b ? b->next : headA;
}
return a;
}
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Output
#2 Code Example with Java Programming
Code -
Java Programming
public class Solution {
public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
ListNode copyA = headA;
ListNode copyB = headB;
while (copyA != copyB) {
copyA = copyA == null ? headB : copyA.next;
copyB = copyB == null ? headA : copyB.next;
}
return copyA;
}
}
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Output
#3 Code Example with Javascript Programming
Code -
Javascript Programming
const getIntersectionNode = function(headA, headB) {
let a = headA, b = headB
while(a !== b) {
a = a == null ? headB : a.next
b = b == null ? headA : b.next
}
return a
};
Input
Output
#4 Code Example with C# Programming
Code -
C# Programming
namespace LeetCode
{
public class _0160_IntersectionOfTwoLinkedLists
{
public ListNode GetIntersectionNode(ListNode headA, ListNode headB)
{
var p1 = headA;
var p2 = headB;
while (p1 != p2)
{
p1 = p1 == null ? headB : p1.next;
p2 = p2 == null ? headA : p2.next;
}
return p1;
}
}
}
Input
Output