如何在C中的二叉搜索树中正确插入/删除？

#include<stdio.h>
#include <stdlib.h>

typedef struct node {
    int data;
    struct node *left;
    struct node *right;
} Node;

Node* createNode(int data) {
    Node* newNode = (Node*) malloc(sizeof(Node));
    newNode->data = data;
    newNode->left = NULL;
    newNode->right = NULL;
    return newNode;
}

Node* insert(Node* root, int data) {
    if (root == NULL) {
        root = createNode(data);
    } else if (data< root->data) {
        root->left = insert(root->left, data);
    } else {
        root->right = insert(root->right, data);
    }
    return root;
}

int main() {
    Node* root = NULL;
    root = insert(root, 50);
    insert(root, 30);
    insert(root, 20);
    insert(root, 40);
    insert(root, 70);
    insert(root, 60);
    insert(root, 80);
    return 0;
}

#include<stdio.h>
#include <stdlib.h>

typedef struct node {
    int data;
    struct node *left;
    struct node *right;
} Node;

Node* findMin(Node* root) {
    while (root->left != NULL) {
        root = root->left;
    }
    return root;
}

Node* deleteNode(Node* root, int data) {
    if (root == NULL) {
        return root;
    }

    if (data< root->data) {
        root->left = deleteNode(root->left, data);
    } else if (data > root->data) {
        root->right = deleteNode(root->right, data);
    } else {
        if (root->left == NULL) {
            Node* temp = root->right;
            free(root);
            return temp;
        } else if (root->right == NULL) {
            Node* temp = root->left;
            free(root);
            return temp;
        }

        Node* temp = findMin(root->right);
        root->data = temp->data;
        root->right = deleteNode(root->right, temp->data);
    }
    return root;
}

int main() {
    Node* root = NULL;
    root = insert(root, 50);
    insert(root, 30);
    insert(root, 20);
    insert(root, 40);
    insert(root, 70);
    insert(root, 60);
    insert(root, 80);

    root = deleteNode(root, 20);
    return 0;
}