二叉树

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

// 二叉树节点的定义
typedef struct TreeNode {
    int data;
    struct TreeNode* left;
    struct TreeNode* right;
} TreeNode;

// 创建新节点
TreeNode* createNode(int data) {
    TreeNode* newNode = (TreeNode*)malloc(sizeof(TreeNode));
    if (newNode == NULL) {
        printf("内存分配失败\n");
        exit(EXIT_FAILURE);
    }
    newNode->data = data;
    newNode->left = NULL;
    newNode->right = NULL;
    return newNode;
}

// 插入节点到二叉搜索树
TreeNode* insert(TreeNode* root, int data) {
    if (root == NULL) {
        return createNode(data);
    }

    if (data < root->data) {
        root->left = insert(root->left, data);
    }
    else if (data > root->data) {
        root->right = insert(root->right, data);
    }

    return root;
}

// 先序遍历
void preOrderTraversal(TreeNode* root) {
    if (root != NULL) {
        printf("%d ", root->data);
        preOrderTraversal(root->left);
        preOrderTraversal(root->right);
    }
}

// 中序遍历
void inOrderTraversal(TreeNode* root) {
    if (root != NULL) {
        inOrderTraversal(root->left);
        printf("%d ", root->data);
        inOrderTraversal(root->right);
    }
}

// 后序遍历
void postOrderTraversal(TreeNode* root) {
    if (root != NULL) {
        postOrderTraversal(root->left);
        postOrderTraversal(root->right);
        printf("%d ", root->data);
    }
}

// 求二叉树的叶子数
int getLeafCount(TreeNode* root) {
    if (root == NULL) {
        return 0;
    }

    if (root->left == NULL && root->right == NULL) {
        return 1; // 叶子节点
    }

    return getLeafCount(root->left) + getLeafCount(root->right);
}

// 求二叉树的深度
int getTreeDepth(TreeNode* root) {
    if (root == NULL) {
        return 0;
    }

    int leftDepth = getTreeDepth(root->left);
    int rightDepth = getTreeDepth(root->right);

    return (leftDepth > rightDepth) ? (leftDepth + 1) : (rightDepth + 1);
}

// 求二叉树中度为一的节点个数
int getDegreeOneCount(TreeNode* root) {
    if (root == NULL) {
        return 0;
    }

    int degreeOneCount = 0;

    if ((root->left == NULL && root->right != NULL) || (root->left != NULL && root->right == NULL)) {
        // 度为一的节点
        degreeOneCount = 1;
    }

    degreeOneCount += getDegreeOneCount(root->left);
    degreeOneCount += getDegreeOneCount(root->right);

    return degreeOneCount;
}

// 销毁二叉树
void destroyTree(TreeNode* root) {
    if (root != NULL) {
        destroyTree(root->left);
        destroyTree(root->right);
        free(root);
    }
}

int main() {
    TreeNode* root = NULL;

    // 插入节点
    root = insert(root, 5);
    root = insert(root, 3);
    root = insert(root, 7);
    root = insert(root, 2);
    root = insert(root, 4);

    // 先序遍历
    printf("先序遍历结果：");
    preOrderTraversal(root);
    printf("\n");

    // 中序遍历
    printf("中序遍历结果：");
    inOrderTraversal(root);
    printf("\n");

    // 后序遍历
    printf("后序遍历结果：");
    postOrderTraversal(root);
    printf("\n");

    // 求叶子数
    int leafCount = getLeafCount(root);
    printf("叶子数：%d\n", leafCount);

    // 求深度
    int depth = getTreeDepth(root);
    printf("树的深度：%d\n", depth);

    // 求度为一的节点个数
    int degreeOneCount = getDegreeOneCount(root);
    printf("度为一的节点个数：%d\n", degreeOneCount);

    // 销毁二叉树
    destroyTree(root);

    return 0;
}