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findIntersection.java
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findIntersection.java
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/*
getKthNode(): get the kth node of the given linked list.
getTailAndSize(): captures both the length and the last node of the given list.
*/
class LinkedListNode {
public LinkedListNode next;
public int val;
public LinkedListNode(int val) {
this.val = val;
}
}
Result getTailAndSize(LinkedListNode list) {
if(list == null) return null;
int size = 1;
LinkedListNode current = list;
while(current.next != null) {
size++;
current = current.next;
}
return new Result(current, size);
}
LinkedListNode getKthNode(LinkedListNode head, int k) {
LinkedListNode current = head;
while(k > 0 && current != null) {
current = current.next;
k--;
}
return current;
}
LinkedListNode findIntersection(LinkedListNode list1, LinkedListNode list2) {
if(list1 == null || list2 == null) return null;
Result result1 = getTailAndSize(list1);
Result result2 = getTailAndSize(list2);
if(result1.tail != resul2.tail) {
return null;
}
LinkedListNode shorter = result1.size() < result2.size() ? list1 : list2;
LinkedListNode longer = result1.size() < result2.size() ? list2 : list1;
longer = getKthNode(longer, Math.abs(result1.size() - result2.size()));
while(shorter != longer) {
shorter = shorter.next;
longer = longer.next;
}
return longer;
}