题解 | #二叉排序树#基本做法

#include <iostream>
using namespace std;

struct BTree
{
    int val;
    struct BTree*lchild,*rchild;
    BTree(int x):val(x),lchild(nullptr),rchild(nullptr){};
};

void createBTree(BTree *&root,int n)
{
    if(root==nullptr) root=new BTree(n);
    else if(n>root->val) createBTree(root->rchild, n);
    else if(n<root->val) createBTree(root->lchild, n);
}

void preOrder(BTree*root)
{
    if(root)
    {
        cout<<root->val<<" ";
        preOrder(root->lchild);
        preOrder(root->rchild);
    }
}

void inOrder(BTree*root)
{
    if(root)
    {
        inOrder(root->lchild);
        cout<<root->val<<" ";
        inOrder(root->rchild);
    }
}

void postOrder(BTree*root)
{
    if(root)
    {
        postOrder(root->lchild);
        postOrder(root->rchild);
        cout<<root->val<<" ";
    }
}

int main() {
    int n;
    int t;
    while(cin>>n)
    {
        BTree*T=nullptr;
        for(int i=0;i<n;i++)
        {
            cin>>t;
            createBTree(T,t);
        }
        preOrder(T);
        cout<<endl;
        inOrder(T);
        cout<<endl;
        postOrder(T);
        cout<<endl;

    }

    return 0;
}
// 64 位输出请用 printf("%lld")