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ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
    if (headA == nullptr || headB == nullptr) {
        return nullptr;
    }
    int lengthA = 1;
    int lengthB = 1;
    ListNode *a = headA;
    ListNode *b = headB;
    while (a->next != nullptr) {
        lengthA++;
        a = a->next;
    }
    while (b->next != nullptr) {
        lengthB++;
        b = b->next;
    }
    if (a != b) {
        return nullptr;
    }
    int dx = abs(lengthA - lengthB);
    a = headA;
    b = headB;
    if (lengthA > lengthB) {
        while (dx--) {
            a = a->next;
        }
    } else if (lengthA < lengthB) {
        while (dx--) {
            b = b->next;
        }
    }
    while (a && b) {
        if (a == b) {
            return a;
        }
        a = a->next;
        b = b->next;
    }
    return nullptr;
}

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

        //跑到最后一个节点，判断是否相同，统计长度
        //相同则有，不同则无
        //长的先跑这部分长度，然后一起跑等相等

        ListNode p = headA, q = headB;

        int lengthA = 1, lengthB = 1;

        while (p.next != null) {
            lengthA ++;
            p = p.next;
        }

        while (q.next != null) {
            lengthB ++;
            q = q.next;
        }

        if(p == q) {
            int length = Math.abs(lengthA - lengthB);

            for (int i = 0; i < length; i ++) {
                if(lengthA > lengthB) {
                    headA = headA.next;
                }else {
                    headB = headB.next;
                }
            }

            while (headA != null && headB != null) {
                if(headA == headB) {
                    return headA;
                }
                headA = headA.next;
                headB = headB.next;
            }

        }

        return null;

    }

int number = 15;
int value = climbStairs(number);
cout << "返回值为："<< value << endl;
return 0;

if( n == 0 || n == 1 || n == 2){
    return n;
}
int num[] = {1,2};
for (int i = 2; i < n; ++i) {
    num[i] = num[i-1] + num[i-2];
    cout << "当前值为：" << num[i] <<endl;
}

return num[n-1];