请用C语言双重指针实现二叉树层级遍历

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

// 定义二叉树结构体
typedef struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
} TreeNode;

// 定义队列结构体
typedef struct QueueNode {
    TreeNode *node;
    struct QueueNode *next;
} QueueNode;
typedef struct Queue {
    QueueNode *front;
    QueueNode *rear;
} Queue;

// 创建二叉树
TreeNode* createTree() {
    int val;
    scanf("%d", &val);
    if (val == -1) { // -1 表示空节点
        return NULL;
    }
    TreeNode *root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = val;
    root->left = createTree();
    root->right = createTree();
    return root;
}

// 初始化队列
void initQueue(Queue **queue) {
    *queue = (Queue*)malloc(sizeof(Queue));
    (*queue)->front = (*queue)->rear = NULL;
}

// 判断队列是否为空
int isEmpty(Queue *queue) {
    return !queue->front;
}

// 入队
void enQueue(Queue *queue, TreeNode *node) {
    QueueNode *newNode = (QueueNode*)malloc(sizeof(QueueNode));
    newNode->node = node;
    newNode->next = NULL;
    if (isEmpty(queue)) {
        queue->front = queue->rear = newNode;
    } else {
        queue->rear->next = newNode;
        queue->rear = newNode;
    }
}

// 出队
TreeNode* deQueue(Queue *queue) {
    if (isEmpty(queue)) {
        return NULL;
    }
    QueueNode *frontNode = queue->front;
    TreeNode *node = frontNode->node;
    queue->front = queue->front->next;
    if (queue->front == NULL) {
        queue->rear = NULL;
    }
    free(frontNode);
    return node;
}

// 层级遍历
void levelOrder(TreeNode *root, int **result, int *returnSize) {
    if (root == NULL) {
        return;
    }
    Queue *queue;
    initQueue(&queue);
    enQueue(queue, root);
    while (!isEmpty(queue)) {
        int size = queue->rear - queue->front + 1; // 当前层的节点个数
        result[*returnSize] = (int*)malloc(sizeof(int) * size);
        for (int i = 0; i < size; i++) {
            TreeNode *node = deQueue(queue);
            result[*returnSize][i] = node->val;
            if (node->left != NULL) {
                enQueue(queue, node->left);
            }
            if (node->right != NULL) {
                enQueue(queue, node->right);
            }
        }
        (*returnSize)++;
    }
}

int main() {
    TreeNode *root = createTree();
    int **result = (int**)malloc(sizeof(int*) * 1000);
    int returnSize = 0;
    levelOrder(root, result, &returnSize);
    for (int i = 0; i < returnSize; i++) {
        for (int j = 0; j < (queue->rear - queue->front + 1); j++) {
            printf("%d ", result[i][j]);
        }
        printf("\n");
    }
    return 0;
}