原题链接: https://oj.leetcode.com/problems/intersection-of-two-linked-lists/

public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
    if (headA == null || headB == null) return null;
    if (headA == headB) return headA;

    ListNode cursorA = headA;
    ListNode cursorB = headB;
    while (cursorA != null && cursorB != null) {
        cursorA = cursorA.next;
        cursorB = cursorB.next;
    }

    ListNode longCursorStart = null;
    ListNode longCursorEnd = null;
    ListNode shortCursor = null;
    if (cursorA != null) {
        longCursorStart = headA;
        longCursorEnd = cursorA;
        shortCursor = headB;
    } else if (cursorB != null) {
        longCursorStart = headB;
        longCursorEnd = cursorB;
        shortCursor = headA;
    } else {
        longCursorStart = headA;
        longCursorEnd = null;
        shortCursor = headB;
    }

    while (longCursorStart != null && longCursorEnd != null) {
        longCursorStart = longCursorStart.next;
        longCursorEnd = longCursorEnd.next;
    }

    while (longCursorStart != shortCursor) {
        longCursorStart = longCursorStart.next;
        shortCursor = shortCursor.next;
    }

    return longCursorStart;
}