16. 求二叉樹層次遍歷

題目：輸入一顆二叉樹，從上往下按層打印樹的每個節點，同一層中按照從左往右的順序打印。代碼如下：

#define MAXLEN 100

void leveltraverse (tree *head) {
    tree *temp = head;
    tree *queue[MAXLEN];
    int rear, front;

    rear = front = 0;
    if (NULL == head)
        return;
    queue[rear++] = head;
    while (rear != front) {
        printf("%d", queue[front]->element);
        if (queue[front] -> left != NULL)
            //insert
        if (queue[front] -> right != NULL)
            //insert
        front = (front + 1) % MAXLEN;
    }
    return;
}