题解 | #二叉排序树#

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
using namespace std;
typedef struct node {
    int num;
    struct node* left;
    struct node* right;
} node, *tree;
void insert(tree& t, int x, int father) {
    if (t == NULL) {
        t = (node*)malloc(sizeof(node));
        t->num = x;
        t->left = NULL;
        t->right = NULL;
        printf("%d\n", father);
        return;
    } else {
        if (t->num >= x) {
            insert(t->left, x, t->num);
        } else {
            insert(t->right, x, t->num);
        }
    }
}
void inorder(tree t) {
    if (t == NULL) {
        return;
    }
    inorder(t->left);
    printf("%d", t->num);
    inorder(t->right);
}
int main() {
    int n;
    while (scanf("%d", &n) != EOF) {
        tree root = NULL;
        while (n--) {
            int x;
            scanf("%d", &x);
            insert(root, x, -1);
        }
    }
    return 0;
}