编写C语言算法，判断一个二叉链储存的二叉树是否为完全二叉树

以下是判断一棵二叉树是否为完全二叉树的C语言算法：

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

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

bool isCompleteTree(TreeNode* root) {
    if (root == NULL) {
        return true;
    }
    TreeNode* queue[10000];
    int front = 0, rear = 0;
    bool flag = false;
    queue[rear++] = root;
    while (front < rear) {
        TreeNode* cur = queue[front++];
        if (cur->left != NULL) {
            if (flag) {
                return false;
            }
            queue[rear++] = cur->left;
        } else {
            flag = true;
        }
        if (cur->right != NULL) {
            if (flag) {
                return false;
            }
            queue[rear++] = cur->right;
        } else {
            flag = true;
        }
    }
    return true;
}

int main() {
    // 构造一棵完全二叉树
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = 1;
    root->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->val = 2;
    root->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->val = 3;
    root->left->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->left->val = 4;
    root->left->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->right->val = 5;
    root->right->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->left->val = 6;
    printf(isCompleteTree(root) ? "是完全二叉树" : "不是完全二叉树");
    return 0;
}

该算法的思路是通过层序遍历二叉树，在遍历过程中判断是否出现了空节点。如果出现了空节点，那么在后面的节点中不应该再出现非空节点；如果后面出现了非空节点，说明该二叉树不是完全二叉树。