1043 Is It a Binary Search Tree （25 分）（二叉查找树）

#include<bits/stdc++.h>

using namespace std;

typedef struct node;

typedef node *tree;

struct node

{

    int data;

    tree L,R;

};

void Insert(tree &bt,int x)

{

    if(bt==NULL){

        bt=new node;

        bt->data=x;

        bt->L=NULL;

        bt->R=NULL;

        return;

    }

    if(x<bt->data) Insert(bt->L,x);

    else Insert(bt->R,x);

}

vector<int>pre1,pre2,post1,post2;

void preorder1(tree bt,vector<int>&p)

{

    if(bt){

        p.push_back(bt->data);

        preorder1(bt->L,p);

        preorder1(bt->R,p);

    }

}

void preorder2(tree bt,vector<int>&p)

{

    if(bt){

        p.push_back(bt->data);

        preorder2(bt->R,p);

        preorder2(bt->L,p);

    }

}

void postorder1(tree bt,vector<int>&p)

{

    if(bt){

        postorder1(bt->L,p);

        postorder1(bt->R,p);

        p.push_back(bt->data);

    }

}

void postorder2(tree bt,vector<int>&p)

{

    if(bt){

        postorder2(bt->R,p);

        postorder2(bt->L,p);

        p.push_back(bt->data);

    }

}

int main()

{

    int n;

    scanf("%d",&n);

    tree bt;

    bt=NULL;

    vector<int>tt;

    for(int i=;i<n;i++){

        int x;

        scanf("%d",&x);

        tt.push_back(x);

        Insert(bt,x);

    }

    preorder1(bt,pre1);

    preorder2(bt,pre2);

    postorder1(bt,post1);

    postorder2(bt,post2);

    if(tt==pre1){

        puts("YES");

        for(int i=;i<post1.size();i++){

            if(i) printf(" ");

            printf("%d",post1[i]);

        }

    }

    else if(tt==pre2){

        puts("YES");

        for(int i=;i<post2.size();i++){

            if(i) printf(" ");

            printf("%d",post2[i]);

        }

    }

    else{

        puts("NO");

    }

    return ;

}