PAT (Advanced Level) Practice 1115 Counting Nodes in a BST

1、建二叉排序树

2、层序遍历，我是把每层的节点数记录下来，最后输出倒数两个

ps：当n=1时，输出“1 + 0 = 1” 

#include 
#include 
#include 
using namespace std;
struct node{
    node* lchild;
    node* rchild;
    int data,layer;
};
void insertNode(int n,node* &root){
    if(root==NULL){
        root = new node;
        root->lchild=NULL;
        root->rchild=NULL;
        root->data=n;
        return;
    }
    if(n<=root->data){
        insertNode(n,root->lchild);
    }else{
        insertNode(n,root->rchild);
    }
}

vector v;
void layerTravel(node* root){
    int layer=0,num=0;
    queue q;
    root->layer=layer;
    q.push(root);
    while(!q.empty()){
        node* Node = q.front();
        q.pop();
        if(Node->lchild!=NULL){
            Node->lchild->layer=Node->layer+1;
            q.push(Node->lchild);
        }
        if(Node->rchild!=NULL){
            Node->rchild->layer=Node->layer+1;
            q.push(Node->rchild);
        }
        if(Node->layer!=layer){
            v.push_back(num);
            num=0;
            layer=Node->layer;
        }
        num++;
    }
    v.push_back(num);
}
int main()
{
    int n;
    cin>>n;
    node* root=NULL;
    for(int i=0;i>m;
        insertNode(m,root);
    }
    layerTravel(root);
    if(v.size()>=2){
        cout<