题解 | #二叉排序树#

#include<iostream>
using namespace std;
typedef struct node {
    int num;
    struct node* left, * right;
    node(int n) :num(n), left(NULL), right(NULL) {}
}TreeNode, * Tree;
void Insert(Tree& root, int num) {
    if (root == NULL) {
        root = (Tree)malloc(sizeof(TreeNode));
        root->left = NULL;
        root->right = NULL;
        root->num = num;
    }
    else
        if (num < root->num)
            Insert(root->left, num);
        else if(num > root->num)
            Insert(root->right, num);
}
void Output1(Tree root) {
    if (root == NULL)
        return;
    cout << root->num << " ";
    Output1(root->left);
    Output1(root->right);
}
void Output2(Tree root) {
    if (root == NULL)
        return;
    Output2(root->left);
    cout << root->num << " ";
    Output2(root->right);
}
void Output3(Tree root) {
    if (root == NULL)
        return;
    Output3(root->left);
    Output3(root->right);
    cout << root->num << " ";
}
int main()
{
    int n, num, ans;
    while (cin >> n) {
        Tree root = NULL;
        for (int i = 0; i < n; ++i) {
            cin >> num;
            Insert(root, num);
        }
        Output1(root);
        cout << endl;
        Output2(root);
        cout << endl;
        Output3(root);
        cout << endl;
    }
}