目录

前言

查找值为x的结点

返回值为指针

返回值为布尔类型

整体代码

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前言

        在二叉树结点个数、叶子结点个数、树的高度、第k层结点个数的计算（C语言）中，我们解决了关于二叉树的部分问题，但是还有一个问题我们放在本篇解决。

查找值为x的结点

返回值为指针

//查找值为x的结点
TreeNode* TreeFind(TreeNode* root, BTDataType x)
{if (root == NULL)return NULL;if (root->data == x)return root;TreeNode* ret1 = TreeFind(root->left, x);if (ret1)return ret1;TreeNode* ret2 = TreeFind(root->right, x);if (ret2)return ret2;return NULL;
}

 

解释：整体过程不再进行文字解释，建议自己画图加深对代码的理解

注意对返回值NULL的处理和理解

返回值为布尔类型

//查找值为x的结点,返回值为布尔类型
bool TreeFind(TreeNode* root, BTDataType x)
{if (root == NULL)return NULL;if (root->data == x)return root;return TreeFind(root->left, x) || TreeFind(root->right, x);
}

 解释：整体过程不再进行文字解释，建议自己画图加深对代码的理解

整体代码

#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <stdbool.h>
typedef int BTDataType;typedef struct BinaryTreeNode
{BTDataType data;struct BinaryTreeNode* left;struct BinaryTreeNode* right;
}TreeNode;TreeNode* BuyTreeNode(int x)
{TreeNode* node = (TreeNode*)malloc(sizeof(TreeNode));assert(node);node->data = x;node->left = NULL;node->right = NULL;return node;
}TreeNode* CreatTree()
{TreeNode* node1 = BuyTreeNode(1);TreeNode* node2 = BuyTreeNode(2);TreeNode* node3 = BuyTreeNode(3);TreeNode* node4 = BuyTreeNode(4);TreeNode* node5 = BuyTreeNode(5);TreeNode* node6 = BuyTreeNode(6);node1->left = node2;node1->right = node4;node2->left = node3;//node2->right = NULL;//node3->left = NULL;//node3->right = NULL;node4->left = node5;node4->right = node6;//node5->left = NULL;//node5->right = NULL;//node6->left = NULL;//node6->right= NULL;return node1;
}void PrevOrder(TreeNode* root)
{if(root == NULL){printf("N ");return;}printf("%d ", root->data);PrevOrder(root->left);PrevOrder(root->right);
}void InOrder(TreeNode* root)
{if (root == NULL){printf("N ");return;}InOrder(root->left);printf("%d ", root->data);InOrder(root->right);
}void LaterOrder(TreeNode* root)
{if (root == NULL){printf("N ");return;}LaterOrder(root->left);LaterOrder(root->right);printf("%d ", root->data);
}//总结点个数
int TreeSize(TreeNode* root)
{return root == NULL ? 0 :TreeSize(root->left) +TreeSize(root->right) + 1;
}//叶子结点个数
int TreeLeafSize(TreeNode* root)
{//空树 返回0if (root == NULL)return 0;//非空树，但是没有左右子树（叶子结点/仅有一个结点的树）返回1if (root->left == NULL && root->right == NULL)return 1;//不是空 也不是叶子结点return TreeLeafSize(root->left) +TreeLeafSize(root->right);
}//树的高度
int TreeHeight(TreeNode* root)
{if (root == NULL)return 0;int leftHeight = TreeHeight(root->left);int rightHeight = TreeHeight(root->right);return leftHeight > rightHeight ? leftHeight + 1 : rightHeight + 1;
}//第k层结点的个数
int TreeLevelK(TreeNode* root,int k)
{assert(k > 0);if (root == NULL)return 0;if (k == 1)return 1;return TreeLevelK(root->left, k - 1) +TreeLevelK(root->right,k-1);
}//查找值为x的结点,返回值为指针
TreeNode* TreeFind(TreeNode* root, BTDataType x)
{if (root == NULL)return NULL;if (root->data == x)return root;TreeNode* ret1 = TreeFind(root->left, x);if (ret1)return ret1;TreeNode* ret2 = TreeFind(root->right, x);if (ret2)return ret2;return NULL;
}查找值为x的结点,返回值为布尔类型
//bool TreeFind(TreeNode* root, BTDataType x)
//{
//	if (root == NULL)
//		return NULL;
//	if (root->data == x)
//		return root;
//
//	return TreeFind(root->left, x) || TreeFind(root->right, x);
//}int main()
{TreeNode* root = CreatTree();//前、中、后序遍历PrevOrder(root);printf("\n");InOrder(root);printf("\n");LaterOrder(root);printf("\n");//获取二叉树中的结点个数 printf("TreeSize：%d\n", TreeSize(root));//叶子结点个数printf("TreeLeafSize：%d\n",TreeLeafSize(root));//树的高度printf("TreeHeight：%d\n", TreeHeight(root));//第k层结点个数int k = 2;printf("TreeLevelK： % d\n", TreeLevelK(root,k));//查找值为x的结点int x = 2;printf("TreeLevelK： % d\n", TreeLevelK(root, x));//查找值为x的结点if (TreeFind(root, 5))printf("找到了\n");elseprintf("没找到\n");return 0;
}

~over~