用c语言编写根据二叉树中序遍历的非递归算法，在二叉树t查找值为x的元素，若找到且其左子树为空，则将值为y的元素插入成为其左孩子，否则若其右孩子为空，则将y插入成为其右孩子。插入失败，返回值为0，否则返回值为1。

好的，根据您的要求，我来为您提供 C 语言的代码实现：

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

// 定义二叉树结构体
typedef struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
} TreeNode;

// 定义栈结构体
typedef struct Stack {
    TreeNode **data;
    int top;
    int maxSize;
} Stack;

// 初始化栈
Stack *initStack(int maxSize) {
    Stack *stack = (Stack*)malloc(sizeof(Stack));
    stack->data = (TreeNode**)malloc(sizeof(TreeNode*) * maxSize);
    stack->top = -1;
    stack->maxSize = maxSize;
    return stack;
}

// 判断栈是否为空
int isEmpty(Stack *stack) {
    return stack->top == -1;
}

// 入栈
void push(Stack *stack, TreeNode *node) {
    if (stack->top == stack->maxSize - 1) {
        return;
    }
    stack->data[++stack->top] = node;
}

// 出栈
TreeNode *pop(Stack *stack) {
    if (isEmpty(stack)) {
        return NULL;
    }
    return stack->data[stack->top--];
}

// 获取栈顶元素
TreeNode *top(Stack *stack) {
    if (isEmpty(stack)) {
        return NULL;
    }
    return stack->data[stack->top];
}

// 遍历二叉树的中序遍历
void inorder(TreeNode *root) {
    Stack *stack = initStack(100);
    TreeNode *p = root;
    while (p || !isEmpty(stack)) {
        while (p) {
            push(stack, p);
            p = p->left;
        }
        if (!isEmpty(stack)) {
            p = pop(stack);
            printf("%d ", p->val);
            p = p->right;
        }
    }
}

// 在二叉树中查找节点
TreeNode *findNode(TreeNode *root, int x) {
    Stack *stack = initStack(100);
    TreeNode *p = root;
    while (p || !isEmpty(stack)) {
        while (p) {
            push(stack, p);
            p = p->left;
        }
        if (!isEmpty(stack)) {
            p = pop(stack);
            if (p->val == x) {
                return p;
            }
            p = p->right;
        }
    }
    return NULL;
}

// 插入节点
int insertNode(TreeNode *root, int x, int y) {
    TreeNode *node = findNode(root, x);
    if (!node) {
        return 0;
    }
    if (!node->left) {
        TreeNode *newNode = (TreeNode*)malloc(sizeof(TreeNode));
        newNode->val = y;
        newNode->left = NULL;
        newNode->right = NULL;
        node->left = newNode;
        return 1;
    } else if (!node->right) {
        TreeNode *newNode = (TreeNode*)malloc(sizeof(TreeNode));
        newNode->val = y;
        newNode->left = NULL;
        newNode->right = NULL;
        node->right = newNode;
        return 1;
    }
    return 0;
}

int main() {
    // 构造二叉树
    TreeNode *root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = 5;
    root->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->val = 3;
    root->left->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->left->val = 1;
    root->left->left->left = NULL;
    root->left->left->right = NULL;
    root->left->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->right->val = 4;
    root->left->right->left = NULL;
    root->left->right->right = NULL;
    root->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->val = 7;
    root->right->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->left->val = 6;
    root->right->left->left = NULL;
    root->right->left->right = NULL;
    root->right->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->right->val = 8;
    root->right->right->left = NULL;
    root->right->right->right = NULL;

    // 遍历二叉树的中序遍历
    inorder(root);
    printf("\n");

    // 在二叉树中查找节点
    TreeNode *node = findNode(root, 4);
    if (node) {
        printf("Find node with value 4.\n");
    } else {
        printf("Not find node with value 4.\n");
    }

    // 插入节点
    int res = insertNode(root, 4, 9);
    if (res) {
        printf("Insert node with value 9 successfully.\n");
    } else {
        printf("Insert node with value 9 failed.\n");
    }

    // 遍历二叉树的中序遍历
    inorder(root);
    printf("\n");

    return 0;
}

以上代码实现了根据二叉树中序遍历的非递归算法，在二叉树中查找值为 x 的元素，若找到且其左子树为空，则将值为 y 的元素插入成为其左孩子，否则若其右孩子为空，则将 y 插入成为其右孩子。若插入失败，则返回值为 0，否则返回值为 1。