1043. Is It a Binary Search Tree (25)

https://www.patest.cn/contests/pat-a-practise/1043

//给定一克BST，构建BST，判断给定的序列是否是构建好的这棵BST的前序序列
/*
如果是的话 :输出这棵树的后序
。。
或者判断这棵树进行左右子树翻转后，如果这棵BST的前序序列是给定的序列，
输出翻转后的这棵树的后序。
*/
#include <iostream>
#include <vector>
using namespace std;
struct node {
int data;
node *lchild;
node *rchild;
};
vector<int> righta,rightb;//前序遍历序列数组
vector<int> seq,post;
void insert(node *&root, int num) {
if ( root == NULL ) {
root = new node();
root->data = num;
root->lchild = NULL;
root->rchild = NULL;
return;
}
if ( num < root->data) {
insert(root->lchild,num);
}
else {
insert(root->rchild,num);
}
}
void preOrder(node *root) {
if ( root == NULL ) return;
righta.push_back(root->data);
preOrder(root->lchild);
preOrder(root->rchild);
}
void ARL(node *root) {
if ( root == NULL ) return;
rightb.push_back(root->data);
ARL(root->rchild);
ARL(root->lchild);
}
void postOrder(node *root) {
if ( root == NULL ) return;
postOrder(root->lchild);
postOrder(root->rchild);
post.push_back(root->data);
}
void Print(vector<int> vc) {
vector<int>::iterator it = vc.begin();
bool flag = true;
for ( ; it != vc.end(); it++) {
if ( flag ) {
printf("%d",(*it));
flag = false;
}else {
printf(" %d",(*it));
}
}
printf("\n");
}

void Change(node *root) {
if ( root == NULL ) return;
node *temp = root->lchild;
root->lchild = root->rchild;
root->rchild = temp;
Change(root->lchild);
Change(root->rchild);
}
int main() {
int n,num;
node *root = NULL;
scanf("%d",&n);
for ( int i = 0; i < n; i++ ) {
scanf("%d",&num);
seq.push_back(num);
insert(root,num);
}
preOrder(root);
ARL(root);
if ( righta == seq ) {
printf("YES\n");
post.clear();
postOrder(root);
Print(post);
}else if ( rightb == seq ) {
printf("YES\n");
Change(root);
postOrder(root);
Print(post);
}
else {
printf("NO\n");
}
return 0;
}