PAT甲1043. Is It a Binary Search Tree (25)

#include <cstdio>
#include <cstdlib>
#include <string.h>
#include <cmath>
#include <algorithm>
#include <string>
#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
using namespace std;

struct node
{
    int data;
    node* lchild;
    node* rchild;
};

int a[1010],N,b[1010],index;

node* newNode(int x)
{
    node* Node=new node;
    Node->data=x;
    Node->lchild=Node->rchild=NULL;
    return Node;
}

void insert(node* &root,int x)
{
    if(root==NULL)
    {
        root=newNode(x);
        return;
    }
    else if(x>=root->data)
    {
        insert(root->rchild,x);
    }
    else if(x<root->data)
    {
        insert(root->lchild,x);
    }
}

node* Create(int a[],int n)
{
    node* root=NULL;
    for(int i=0;i<n;i++)
    {
        insert(root,a[i]);
    }
    return root;
}

void PreOrder(node* root)
{
    if(root==NULL)return;
    b[index++]=root->data;
    PreOrder(root->lchild);
    PreOrder(root->rchild);
}

void PreOrderIn(node* root)
{
    if(root==NULL)return;
    b[index++]=root->data;
    PreOrderIn(root->rchild);
    PreOrderIn(root->lchild);
}

void postOrder(node* root,bool In)
{
    if(root==NULL)return;

    if(!In)
    {
        postOrder(root->lchild,In);
        postOrder(root->rchild,In);
    }
    else
    {
        postOrder(root->rchild,In);
        postOrder(root->lchild,In);
    }
    printf("%d",root->data);
    if(index!=N-1)
        printf(" ");
    index++;
}

bool cmpab(int a[],int b[] ,int n)
{
    for(int i=0;i<n;i++)
    {
        if(a[i]!=b[i])
            return false;
    }
    return true;
}

int main()  
{   
    scanf("%d",&N);
    for(int i=0;i<N;i++)
    {
        scanf("%d",&a[i]);
    }
    node* root=Create(a,N);
    index=0;
    PreOrder(root);
    bool Flag=false;
    bool In=false;
    if(cmpab(a,b,N))
    {
        Flag=true;
    }
    else
    {
        index=0;
        PreOrderIn(root);
        if(cmpab(a,b,N))
        {
            Flag=true;
            In=true;
        }
    }
    if(Flag)
    {
        printf("YES\n");
        index=0;
        postOrder(root,In);
    }
    else
    {
        printf("NO\n");
    }
    system("pause");
    return 0;
}