二叉树 (Binary Tree)相关题目(求总节点数 叶子节点数 深度 第k层节点数)

1.求二叉树中节点个数

2.求二叉树叶子节点个数

3.求二叉树的深度

4.求二叉树第K层的节点个数

#include <stdio.h>#include <stdlib.h>#define ElementType chartypedef struct Node {    ElementType data;    struct Node *lchild;    struct Node *rchild;}BinaryTree;//创建二叉树节点BinaryTree* CreateBinaryTree(data) {    BinaryTree* t = (BinaryTree*)malloc(sizeof(BinaryTree));    if (!t) {        printf("空间不足！\n");        return NULL;    }    t->lchild = NULL;    t->rchild = NULL;    t->data = data;    return t;}/* 求二叉树中节点个数 递归解法： （1）如果二叉树为空，节点个数为0 （2）如果二叉树不为空，二叉树节点个数 = 左子树节点个数 + 右子树节点个数 + 1*/int GetNodeNum(BinaryTree* BT) {    if (BT == NULL)        return 0;    int leftNum = GetNodeNum(BT->lchild); //左子树节点个数    int rightNum = GetNodeNum(BT->rchild); //右子树节点个数    return (leftNum + rightNum + 1);}/* 求二叉树叶子节点个数 递归解法： （1）如果二叉树为空，返回0 （2）如果二叉树不为空且左右子树为空，返回1 （3）如果二叉树不为空，且左右子树不同时为空，返回左子树中叶子节点个数加上右子树中叶子节点个数*/int GetLeafNodeNum(BinaryTree* BT) {    if (BT == NULL)        return 0;    if (BT->lchild == NULL && BT->rchild == NULL)        return 1;    int leftNum = GetLeafNodeNum(BT->lchild); //左子树中叶子节点个数    int rightNum = GetLeafNodeNum(BT->rchild); //右子树中叶子节点个数    return (leftNum + rightNum);}/* 求二叉树的深度 递归解法： （1）如果二叉树为空，二叉树的深度为0 （2）如果二叉树不为空，二叉树的深度 = max(左子树深度， 右子树深度) + 1*/int GetDepth(BinaryTree* BT) {    if (BT == NULL)        return 0;    int leftDepth = GetDepth(BT->lchild); //左子树深度    int rightDepth = GetDepth(BT->rchild); //右子树深度    int maxDepth = (leftDepth > rightDepth) ? leftDepth : rightDepth;    return (maxDepth + 1);}/* 求二叉树第K层的节点个数 递归解法： （1）如果二叉树为空或者k<1返回0 （2）如果二叉树不为空并且k==1，返回1 （3）如果二叉树不为空且k>1，返回左子树中k-1层的节点个数与右子树k-1层节点个数之和*/int GetNodeNumKthLevel(BinaryTree* BT, int k) {    if (BT == NULL || k < 1)        return 0;    if (k == 1)        return 1;    int leftNum = GetNodeNumKthLevel(BT->lchild, k - 1);    int rightNum = GetNodeNumKthLevel(BT->rchild, k - 1);    return (leftNum + rightNum);}int main(int argc, const char * argv[]) {    BinaryTree* tree_A = CreateBinaryTree('A');        BinaryTree* tree_B = CreateBinaryTree('B');    tree_A->lchild = tree_B;        BinaryTree* tree_C = CreateBinaryTree('C');    tree_A->rchild = tree_C;        BinaryTree* tree_D = CreateBinaryTree('D');    tree_B->lchild = tree_D;        BinaryTree* tree_F = CreateBinaryTree('F');    tree_B->rchild = tree_F;        BinaryTree* tree_E = CreateBinaryTree('E');    tree_F->lchild = tree_E;        BinaryTree* tree_G = CreateBinaryTree('G');    tree_C->lchild = tree_G;        BinaryTree* tree_I = CreateBinaryTree('I');    tree_C->rchild = tree_I;        BinaryTree* tree_H = CreateBinaryTree('H');    tree_G->rchild = tree_H;        int num = GetNodeNum(tree_A);    printf("二叉树节点个数：%d", num);        int depth = GetDepth(tree_A);    printf("\n二叉树深度：%d", depth);        int k = 3;    int kthNum  = GetNodeNumKthLevel(tree_A, k);    printf("\n二叉树第%d层节点数：%d", k, kthNum);        int leafNum = GetLeafNodeNum(tree_A);    printf("\n二叉树叶子节点个数：%d", leafNum);        return 0;}