题解 | #二叉排序树#

#include <iostream>
using namespace std;
struct node {
    int data;
    node* leftChild;
    node* rightChild;
    node(int a) {
        data = a;
        leftChild = NULL;
        rightChild = NULL;
    }
};
int father;
node* insert(int a, node* root, int f) {
    if (root == NULL) {
        node* newNode = new node(a);
        father = f;
        return newNode;
    }
    if (a < root->data) root->leftChild = insert(a, root->leftChild, root->data);
    else root->rightChild = insert(a, root->rightChild, root->data);
    return root;
}
int main() {
    int n;
    while (cin >> n) { // 注意 while 处理多个 case
        node* root = NULL;
        while (n--) {
            int temp;
            cin >> temp;
            root = insert(temp, root, -1);
            cout << father << endl;
        }
    }
}
// 64 位输出请用 printf("%lld")