题解 | #二叉排序树#

#include<cstdio>
#include<string>

struct TreeNode {
    int data;
    TreeNode* LChild;
    TreeNode* RChild;
};
void InsertBST(TreeNode*& root, int data) {
    TreeNode* pa = new TreeNode;
    pa->data = data;
    pa->LChild = NULL;
    pa->RChild = NULL;
    if (root == NULL) {
        root = pa;
        printf("-1\n");
    } else {
        TreeNode* ppre = root;
        TreeNode* pcur;
        while (true) {
            if (data < ppre->data) {
                pcur = ppre->LChild;
                if (pcur == NULL) {
                    ppre ->LChild = pa;
                    printf("%d\n", ppre->data);
                    break;
                } else {
                    ppre = pcur;
                }
            } else {
                pcur = ppre->RChild;
                if (pcur == NULL) {
                    ppre->RChild = pa;
                    printf("%d\n", ppre->data);
                    break;
                } else {
                    ppre = pcur;
                }
            }
        }
    }
}
int main() {
    TreeNode* root = NULL;
    int n ;
    scanf("%d", &n);
    for (int i = 0 ; i < n; ++i) {
        int arr;
        scanf("%d", &arr);
        InsertBST(root, arr);
    }
}