PAT甲級 1043 Is It a Binary Search Tree (二叉查找樹）

#include <iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
#include<string>
#include <map>
#define LL long long
using namespace std;

struct node{
    int data;//數據域
    node *left, *right;//指針域
};
//爲了能修改節點，需要傳引用
void Insert(node*& root, int x){
    if(root == NULL){//邊界條件，沒找到即爲插入位置
        root = new node;
        root->data = x;
        root->left = root->right = NULL;
        return;//別忘了返回！~
    }
    if(root->data > x)
        Insert(root->left, x);
    else
        Insert(root->right, x);
}

//先序遍歷，結果存在vi
void preOrder(node* root, vector<int>&vi){
    if(root == NULL) return;
    vi.push_back(root->data);
    preOrder(root->left, vi);
    preOrder(root->right, vi);
}
//鏡像樹先序遍歷，結果存在vi
void preOrderMirror(node* root, vector<int>&vi) {
    if(root == NULL) return;
    vi.push_back(root->data);
    preOrderMirror(root->right, vi);
    preOrderMirror(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 postOrderMirror(node* root, vector<int>&vi){
    if(root == NULL) return;
    postOrderMirror(root->right, vi);
    postOrderMirror(root->left, vi);
    vi.push_back(root->data);
}

vector<int> origin, pre, preM, post, postM;

int main(){
    int n;
    scanf("%d", &n);
    node* root = NULL;//定義頭結點
    for(int i = 0; i < n; i++){
        int x;
        scanf("%d", &x);
        Insert(root, x);
        origin.push_back(x);
    }
    preOrder(root, pre);
    preOrderMirror(root, preM);
    postOrder(root, post);
    postOrderMirror(root, postM);
    if(pre == origin){
        printf("YES\n");
        for(int i = 0; i < post.size(); i++){
            if(i) printf(" ");
            printf("%d", post[i]);
        }
    }
    else if(preM == origin){
        printf("YES\n");
        for(int i = 0; i < postM.size(); i++){
            if(i) printf(" ");
            printf("%d", postM[i]);
        }
    }
    else printf("NO\n");
    return 0;
}