利用递归遍历算法建立一颗二元树，输出先序遍历序列及该二元树中全部的叶子节点 c语言

好的，以下是利用递归遍历算法建立一棵二叉树，输出先序遍历序列及该二叉树中全部叶子节点的 C 语言代码：

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

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

struct TreeNode* buildTree(int* preorder, int preorderSize, int* inorder, int inorderSize) {
    if (preorderSize == 0 || inorderSize == 0) {
        return NULL;
    }
    int rootVal = preorder[0];
    struct TreeNode *root = (struct TreeNode *)malloc(sizeof(struct TreeNode));
    root->val = rootVal;
    int i;
    for (i = 0; i < inorderSize; i++) {
        if (inorder[i] == rootVal) {
            break;
        }
    }
    root->left = buildTree(preorder + 1, i, inorder, i);
    root->right = buildTree(preorder + 1 + i, preorderSize - i - 1, inorder + i + 1, inorderSize - i - 1);
    return root;
}

void preorderTraversal(struct TreeNode* root) {
    if (root == NULL) {
        return;
    }
    printf("%d ", root->val);
    preorderTraversal(root->left);
    preorderTraversal(root->right);
}

void getLeafNodes(struct TreeNode* root, int* result, int* returnSize) {
    if (root == NULL) {
        return;
    }
    if (root->left == NULL && root->right == NULL) {
        result[(*returnSize)++] = root->val;
        return;
    }
    getLeafNodes(root->left, result, returnSize);
    getLeafNodes(root->right, result, returnSize);
}

int main() {
    int preorder[] = {1, 2, 4, 5, 3, 6, 7};
    int inorder[] = {4, 2, 5, 1, 6, 3, 7};
    int preorderSize = sizeof(preorder) / sizeof(int);
    int inorderSize = sizeof(inorder) / sizeof(int);
    struct TreeNode *root = buildTree(preorder, preorderSize, inorder, inorderSize);
    preorderTraversal(root);
    printf("\n");
    int leafNodes[preorderSize];
    int returnSize = 0;
    getLeafNodes(root, leafNodes, &returnSize);
    for (int i = 0; i < returnSize; i++) {
        printf("%d ", leafNodes[i]);
    }
    printf("\n");
    return 0;
}

以上代码中，`buildTree` 函数用于建立二叉树，`preorderTraversal` 函数用于输出二叉树的先序遍历序列，`getLeafNodes` 函数用于获取二叉树中所有的叶子节点。`main` 函数中定义了二叉树的先序遍历数组 `preorder` 和中序遍历数组 `inorder`，并分别计算了它们的大小。在 `main` 函数中，首先建立二叉树，然后输出先序遍历序列和所有叶子节点。