C语言层序创建二叉树

以下是C语言层序创建二叉树的示例代码：

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

#define MAX_SIZE 100

/* 节点结构 */
typedef struct node {
    char a;
    struct node* leftchild, * rightchild;
} Bitree;

/* 队列结构 */
typedef struct queue {
    Bitree* data[MAX_SIZE];
    int front, rear;
} Queue;

/* 初始化队列 */
void initQueue(Queue* q) {
    q->front = q->rear = 0;
}

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

/* 入队 */
void enQueue(Queue* q, Bitree* node) {
    if ((q->rear + 1) % MAX_SIZE == q->front) {
        printf("Queue is full.\n");
        return;
    }
    q->data[q->rear] = node;
    q->rear = (q->rear + 1) % MAX_SIZE;
}

/* 出队 */
Bitree* deQueue(Queue* q) {
    if (isEmpty(q)) {
        printf("Queue is empty.\n");
        return NULL;
    }
    Bitree* res = q->data[q->front];
    q->front = (q->front + 1) % MAX_SIZE;
    return res;
}

/* 层序创建二叉树 */
void create(Bitree** T) {
    Queue q;
    initQueue(&q);
    char a;
    scanf("%c", &a);
    if (a == '#') {
        *T = NULL;
        return;
    }
    *T = (Bitree*)malloc(sizeof(Bitree));
    (*T)->a = a;
    (*T)->leftchild = (*T)->rightchild = NULL;
    enQueue(&q, *T);
    while (!isEmpty(&q)) {
        Bitree* node = deQueue(&q);
        scanf("%c", &a);
        if (a == '#') {
            node->leftchild = NULL;
        }
        else {
            node->leftchild = (Bitree*)malloc(sizeof(Bitree));
            node->leftchild->a = a;
            node->leftchild->leftchild = node->leftchild->rightchild = NULL;
            enQueue(&q, node->leftchild);
        }
        scanf("%c", &a);
        if (a == '#') {
            node->rightchild = NULL;
        }
        else {
            node->rightchild = (Bitree*)malloc(sizeof(Bitree));
            node->rightchild->a = a;
            node->rightchild->leftchild = node->rightchild->rightchild = NULL;
            enQueue(&q, node->rightchild);
        }
    }
}

/* 先序遍历 */
void preOrder(Bitree* T) {
    if (T == NULL) {
        return;
    }
    printf("%c ", T->a);
    preOrder(T->leftchild);
    preOrder(T->rightchild);
}

int main() {
    Bitree* T;
    create(&T);
    printf("先序遍历结果：");
    preOrder(T);
    printf("\n");
    return 0;
}