Question
Write a program to find the node at which the intersection of two singly linked lists begins.
For example, the following two linked lists:
A: a1 → a2
↘
c1 → c2 → c3
↗
B: b1 → b2 → b3
begin to intersect at node c1.
Notes:
- If the two linked lists have no intersection at all, return null.
- The linked lists must retain their original structure after the function returns.
- You may assume there are no cycles anywhere in the entire linked structure.
- Your code should preferably run in O(n) time and use only O(1) memory.
Solution
TODO
Code
public class Solution {
public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
ListNode tA = headA;
ListNode tB = headB;
int lA = 0;
int lB = 0;
while(tA != null) {
tA = tA.next;
lA++;
}
while(tB != null) {
tB = tB.next;
lB++;
}
int diff = Math.abs(lA - lB);
ListNode nS = headA;
ListNode nL = headB;
if(lA > lB) {
nS = headB;
nL = headA;
}
while(diff > 0) {
nL = nL.next;
diff --;
}
while(nS != nL) {
nS = nS.next;
nL = nL.next;
}
return nS;
}
}
Performance
TODO