已知二叉树的先序序列，输出层序遍历序列。c语言数据结构代码

已知二叉树的先序序列，输出层序遍历序列的C语言代码如下：

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

#define MAX_SIZE 100

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

typedef struct Queue {
    TreeNode* data[MAX_SIZE];
    int front;
    int rear;
} Queue;

void initQueue(Queue* q) {
    q->front = 0;
    q->rear = 0;
}

int isEmpty(Queue* q) {
    return q->front == q->rear;
}

int isFull(Queue* q) {
    return (q->rear + 1) % MAX_SIZE == q->front;
}

void enqueue(Queue* q, TreeNode* node) {
    if (isFull(q)) {
        return;
    }
    q->data[q->rear] = node;
    q->rear = (q->rear + 1) % MAX_SIZE;
}

TreeNode* dequeue(Queue* q) {
    if (isEmpty(q)) {
        return NULL;
    }
    TreeNode* node = q->data[q->front];
    q->front = (q->front + 1) % MAX_SIZE;
    return node;
}

TreeNode* buildTree(char* preorder, char* inorder, int size) {
    if (size == 0) {
        return NULL;
    }
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = *preorder;
    int rootIndex = 0;
    while (*(inorder + rootIndex) != *preorder) {
        rootIndex++;
    }
    root->left = buildTree(preorder + 1, inorder, rootIndex);
    root->right = buildTree(preorder + rootIndex + 1, inorder + rootIndex + 1, size - rootIndex - 1);
    return root;
}

void levelOrder(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    Queue q;
    initQueue(&q);
    enqueue(&q, root);
    while (!isEmpty(&q)) {
        TreeNode* node = dequeue(&q);
        printf("%c ", node->val);
        if (node->left != NULL) {
            enqueue(&q, node->left);
        }
        if (node->right != NULL) {
            enqueue(&q, node->right);
        }
    }
}

int main() {
    char preorder[] = "ABDECF";
    char inorder[] = "DBEAFC";
    TreeNode* root = buildTree(preorder, inorder, sizeof(preorder) / sizeof(char));
    levelOrder(root);
    return 0;
}