题解 | #二叉排序树#

#include<iostream>
using namespace std;

struct Treenode{
    int data;
    Treenode* leftchild;
    Treenode* rightchild;
    Treenode(int c):data(c),leftchild(NULL),rightchild(NULL){}
};

Treenode* insert(Treenode* root,int x,int father){
    if(root==NULL){  //创建新结点
        root=new Treenode(x);
        cout<<father<<endl;  //输出父结点
    }else if(root->data>x){  //插入左子树
        root->leftchild=insert(root->leftchild,x,root->data);
    }else{  //插入右子树
        root->rightchild=insert(root->rightchild,x,root->data);
    }
    return root;
}

int main(){
    int n;
    while(cin>>n){
        Treenode * root=NULL;  //建立空树
        for(int i=0;i<n;i++){  //逐个插入
            int x;
            cin>>x;
            root=insert(root,x,-1);
        }
    }
    return 0;
}