PAT A1043 Is It a Binary Search Tree (25分)(二叉搜索树的建立）

二叉搜索树的建立只能够用链表不能用数组

#include<cstdio>
#include<vector>
using namespace std;
const int N = 1010;
struct node{
    int data;
    node* left=NULL;
    node* right=NULL;
};
int n;
vector<int> seq,pre,preM,post,postM;

void insert(node* &root,int data){
    if(root==NULL){
        root = new node;
        root->data = data;
        return;
    }
    if(root->data <= data)  insert(root->right,data);
    if(root->data > data) insert(root->left,data);
    return;
}

void preOrder(node *root,vector<int> &vi){
    if(root==NULL) return;
    vi.push_back(root->data);
    preOrder(root->left,vi);
    preOrder(root->right,vi);
}

void preOrderM(node *root,vector<int> &vi){
    if(root==NULL) return;
    vi.push_back(root->data);
    preOrderM(root->right,vi);
    preOrderM(root->left,vi);
}

void postOrder(node *root,vector<int> &vi){
    if(root==NULL) return;
    postOrder(root->left,vi);
    postOrder(root->right,vi);
    vi.push_back(root->data);
}

void postOrderM(node *root,vector<int> &vi){
    if(root==NULL) return;
    postOrderM(root->right,vi);
    postOrderM(root->left,vi);
    vi.push_back(root->data);

}
int main(){
    scanf("%d",&n);
    node* root=NULL;
    for(int i=0;i<n;i++){
        int data;
        scanf("%d",&data);
        seq.push_back(data);
        insert(root,data);
    }
    preOrder(root,pre);
    preOrderM(root,preM);
    postOrder(root,post);
    postOrderM(root,postM);
    if(seq==pre){
        printf("YES\n");
        for(int i = 0;i<post.size();i++){
            printf("%d",post[i]);
            if(i!=post.size()-1) printf(" ");
        }
    }else if(seq==preM){
        printf("YES\n");
        for(int i = 0;i<postM.size();i++){
            printf("%d",postM[i]);
            if(i!=postM.size()-1) printf(" ");
        }        
    }else{
        printf("NO\n");
    }
    return 0;
}