用c语言编写先序遍历二叉树的递归算法,以及计算二叉树中度为1的结点个数的算法。

以下是C语言编写先序遍历二叉树的递归算法和计算二叉树中度为1的结点个数的算法：

1. 先序遍历二叉树的递归算法

#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;

// 先序遍历二叉树的递归算法
void preorderTraversal(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    printf("%d ", root->val); // 访问根节点
    preorderTraversal(root->left); // 遍历左子树
    preorderTraversal(root->right); // 遍历右子树
}

int main() {
    // 构建二叉树
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = 1;    root->left = (TreeNode*)malloc(sizeof(TreeNode));    root->left->val = 2;
    root->left->left = NULL;
    root->left->right = NULL;
    root->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->val = 3;
    root->right->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->left->val = 4;
    root->right->left->left = NULL;
    root->right->left->right = NULL;
    root->right->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->right->val = 5;
    root->right->right->left = NULL;
    root->right->right->right = NULL;

    // 先序遍历二叉树
    printf("先序遍历结果：");
    preorderTraversal(root);
    printf("\n");

    return 0;
}

2. 计算二叉树中度为1的结点个数的算法

#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;

// 计算二叉树中度为1的结点个数的算法
int countDegreeOne(TreeNode* root) {
    if (root == NULL) {
        return 0;
    }
    int count = 0;
    if ((root->left == NULL && root->right != NULL) || (root->left != NULL && root->right == NULL)) {
        count++;
    }
    count += countDegreeOne(root->left);
    count += countDegreeOne(root->right);
    return count;
}

int main() {
    // 构建二叉树
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = 1;
    root->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->val = 2;
    root->left->left = NULL;
    root->left->right = NULL;
    root->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->val = 3;
    root->right->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->left->val = 4;
    root->right->left->left = NULL;
    root->right->left->right = NULL;
    root->right->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->right->val = 5;
    root->right->right->left = NULL;
    root->right->right->right = NULL;

    // 计算二叉树中度为1的结点个数
    int count = countDegreeOne(root);
    printf("度为1的结点个数：%d\n", count);

    return 0;
}