c语言-构建一个静态二叉树

第一、树的构建

定义树结构

struct BTNode {
	char data;
	struct BTNode* pLChild;
	struct BTNode* pRChild;
};

静态方式创建一个简单的二叉树

struct BTNode* create_list() {

	struct  BTNode* pA = (struct BTNode*)malloc(sizeof(BTNode));
	struct  BTNode* pB = (struct BTNode*)malloc(sizeof(BTNode));
	struct  BTNode* pC = (struct BTNode*)malloc(sizeof(BTNode));
	struct  BTNode* pD = (struct BTNode*)malloc(sizeof(BTNode));
	struct  BTNode* pE = (struct BTNode*)malloc(sizeof(BTNode));

	pA->data = 'A';
	pB->data = 'B';
	pC->data = 'C';
	pD->data = 'D';
	pE->data = 'E';	

	pA->pLChild = pB;
	pA->pRChild = pC;
	pB->pLChild = pB->pRChild = NULL;

	pC->pLChild = pD;
	pC->pRChild = NULL;

	pD->pLChild = NULL;
	pD->pRChild = pE;

	pE->pLChild = pE->pRChild = NULL;

	return pA;
}

　　

第二、树的三种遍历

1. 先序遍历

//先序输出
void PreTravense(struct BTNode* pHead) {
	if (NULL!= pHead)
	{
		printf("%c", pHead->data);
		if (NULL!= pHead->pLChild)
		{
			PreTravense(pHead->pLChild);
		}
		if (NULL != pHead->pRChild)
		{
			PreTravense(pHead->pRChild);
		}
	}
}

　　

2. 中序遍历

//中序输出
void InTravense(struct BTNode* pHead) {
	if (NULL != pHead)
	{
		if (NULL != pHead->pLChild)
		{
			PreTravense(pHead->pLChild);
		}
		printf("%c", pHead->data);

		if (NULL != pHead->pRChild)
		{
			PreTravense(pHead->pRChild);
		}
	}
}

　　

3.后续遍历

//后序输出
void PostTravense(struct BTNode* pHead) {
	if (NULL != pHead)
	{
		if (NULL != pHead->pLChild)
		{
			PreTravense(pHead->pLChild);
		}		

		if (NULL != pHead->pRChild)
		{
			PreTravense(pHead->pRChild);
		}
		printf("%c", pHead->data);
	}
}

第三、最终运行测试

int main() {
	printf("创建序列\n");
	struct BTNode* pHead = create_list();

	printf("先序输出\n");
	PreTravense(pHead);
	printf("中序输出\n");
	InTravense(pHead);
	printf("后序输出\n");
	PostTravense(pHead);
	return 0;
}