画出自己的一颗二叉树，给出输入序列；把中序或后序的遍历算法改为非递归算法；给出遍历序列。

好的,我来为您解答这个问题,并提供相应的C语言代码实现。

1. 画出二叉树并给出输入序列

我们可以先定义一个简单的二叉树结构:

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

struct TreeNode* createTree() {
    struct TreeNode* root = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->val = 1;
    
    root->left = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->left->val = 2;
    
    root->right = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->right->val = 3;
    
    root->left->left = NULL;
    root->left->right = NULL;
    
    root->right->left = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->right->left->val = 4;
    
    root->right->right = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->right->right->val = 5;
    
    root->right->left->left = NULL;
    root->right->left->right = NULL;
    
    root->right->right->left = NULL;
    root->right->right->right = NULL;
    
    return root;
}

这个函数创建了一棵简单的二叉树:

    1
   / \
  2   3
     / \
    4   5

输入序列就是创建这棵树的顺序:[1, 2, 3, 4, 5]

2. 将中序遍历改为非递归算法

中序遍历的非递归实现通常使用栈:

void inorderTraversal(struct TreeNode* root) {
    struct TreeNode* current = root;
    struct TreeNode* stack[100];
    int top = -1;
    
    while (current != NULL || top != -1) {
        while (current != NULL) {
            stack[++top] = current;
            current = current->left;
        }
        current = stack[top--];
        printf("%d ", current->val);
        current = current->right;
    }
}

3. 将后序遍历改为非递归算法

后序遍历的非递归实现稍微复杂一些,可以使用两个栈:

void postorderTraversal(struct TreeNode* root) {
    if (root == NULL) return;
    
    struct TreeNode* stack1[100];
    struct TreeNode* stack2[100];
    int top1 = -1, top2 = -1;
    
    stack1[++top1] = root;
    
    while (top1 != -1) {
        struct TreeNode* node = stack1[top1--];
        stack2[++top2] = node;
        
        if (node->left != NULL) {
            stack1[++top1] = node->left;
        }
        if (node->right != NULL) {
            stack1[++top1] = node->right;
        }
    }
    
    while (top2 != -1) {
        struct TreeNode* node = stack2[top2--];
        printf("%d ", node->val);
    }
}

4. 遍历序列

使用上述非递归遍历算法,得到的遍历序列如下:

- 中序遍历: 2 1 4 3 5
- 后序遍历: 2 4 5 3 1