C语言层次遍历创建二叉树

语言中，层次遍历创建二叉树的过程可以通过队列来实现。具体步骤如下：

1. 定义二叉树结构体和队列结构体，以及相应的入队和出队操作函数。

typedef struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
} TreeNode;

typedef struct QueueNode {
    TreeNode *node;
    struct QueueNode *next;
} QueueNode;

typedef struct Queue {
    QueueNode *front;
    QueueNode *rear;
} Queue;

void enqueue(Queue *q, TreeNode *node) {
    QueueNode *newNode = (QueueNode*)malloc(sizeof(QueueNode));
    newNode->node = node;
    newNode->next = NULL;
    if (q->rear) {
        q->rear->next = newNode;
    } else {
        q->front = newNode;
    }
    q->rear = newNode;
}

TreeNode* dequeue(Queue *q) {
    if (!q->front) {
        return NULL;
    }
    TreeNode *node = q->front->node;
    QueueNode *temp = q->front;
    q->front = q->front->next;
    if (!q->front) {
        q->rear = NULL;
    }
    free(temp);
    return node;
}

2. 定义层次遍历创建二叉树的函数，函数参数为一个整型数组和数组长度，返回值为二叉树的根节点。

TreeNode* createTree(int *nums, int numsSize) {
    if (numsSize == 0) {
        return NULL;
    }
    TreeNode *root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = nums[0];
    root->left = NULL;
    root->right = NULL;
    Queue q = {NULL, NULL};
    enqueue(&q, root);
    int i = 1;
    while (i < numsSize) {
        TreeNode *parent = dequeue(&q);
        if (i < numsSize) {
            TreeNode *left = (TreeNode*)malloc(sizeof(TreeNode));
            left->val = nums[i++];
            left->left = NULL;
            left->right = NULL;
            parent->left = left;
            enqueue(&q, left);
        }
        if (i < numsSize) {
            TreeNode *right = (TreeNode*)malloc(sizeof(TreeNode));
            right->val = nums[i++];
            right->left = NULL;
            right->right = NULL;
            parent->right = right;
            enqueue(&q, right);
        }
    }
    return root;
}

3. 调用层次遍历创建二叉树的函数，传入一个整型数组和数组长度，即可得到创建好的二叉树的根节点。

int nums[] = {1, 2, 3, 4, 5, 6, 7};
int numsSize = sizeof(nums) / sizeof(int);
TreeNode *root = createTree(nums, numsSize);