给我二叉树层次遍历的c++代码

当然，下面是二叉树层次遍历的C代码：

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

//树节点的结构体
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

//队列节点的结构体
struct QueueNode {
    struct TreeNode *data;
    struct QueueNode *next;
};

//队列的结构体
struct Queue {
    struct QueueNode *front;
    struct QueueNode *rear;
};

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

//入队操作
void enQueue(struct Queue *q, struct TreeNode *data) {
    struct QueueNode *node = (struct QueueNode*)malloc(sizeof(struct QueueNode));
    node->data = data;
    node->next = NULL;
    if(q->rear == NULL) {
        q->front = node;
        q->rear = node;
    } else {
        q->rear->next = node;
        q->rear = node;
    }
}

//出队操作
struct TreeNode* deQueue(struct Queue *q) {
    if(q->front == NULL) {
        return NULL;
    }
    struct QueueNode *node = q->front;
    if(q->front == q->rear) {
        q->front = NULL;
        q->rear = NULL;
    } else {
        q->front = q->front->next;
    }
    struct TreeNode *data = node->data;
    free(node);
    return data;
}

int** levelOrder(struct TreeNode* root, int* returnSize, int** returnColumnSizes){
    //定义一个二维数组来保存遍历结果
    int **result = (int**)malloc(sizeof(int*) * 1000);
    *returnColumnSizes = (int*)malloc(sizeof(int) * 1000);
    struct Queue q;
    *returnSize = 0;
    if(root == NULL) {
        return result;
    }
    initQueue(&q);
    enQueue(&q, root);
    while(q.front != NULL) {
        int size = q.rear - q.front + 1;
        int *temp = (int*)malloc(sizeof(int) * size);
        for(int i = 0; i < size; i++) {
            struct TreeNode *node = deQueue(&q);
            temp[i] = node->val;
            if(node->left != NULL) {
                enQueue(&q, node->left);
            }
            if(node->right != NULL) {
                enQueue(&q, node->right);
            }
        }
        (*returnColumnSizes)[*returnSize] = size;
        result[*returnSize] = temp;
        (*returnSize)++;
    }
    return result;
}

希望能够帮到您！