数据结构--二叉树代码实现（建立，前序，中序，后续遍历，树的深度，销毁）

代码的树的结构为

                                        1

                              2             3

                     4          5     6         7

              8

#include 
#include 
#include 

/* 结构体 */
typedef struct treenode
{
    struct treenode *pstLeftChild;
    struct treenode *pstRightChild;
    int idata;
}TreeNode_S,TreeHead_S;

/* 初始化树 */
TreeHead_S *InitTree(TreeNode_S *pstNode)
{
    TreeHead_S *tree = pstNode;
    return tree;
}

/* 创建树的节点 */
TreeNode_S *CreateTreeNode(int idata, TreeNode_S *pstleftchild, TreeNode_S *pstrightchild)
{
    TreeNode_S *pstNewNode;

    pstNewNode = malloc(sizeof(TreeNode_S));
    if (pstNewNode != NULL)
    {
        pstNewNode->idata = idata;
        pstNewNode->pstLeftChild = pstleftchild;
        pstNewNode->pstRightChild = pstrightchild;
    }

    return pstNewNode;
}

/* 销毁树节点 */
void DestroyTreeNode(TreeNode_S *pstTreeNode)
{
    if (pstTreeNode != NULL)
    {
        printf("%d ", pstTreeNode->idata);
        free(pstTreeNode);
    }

    return;
}

/* 销毁树*/
void DestroyTree(TreeHead_S *pstTreeHead)
{
    if (pstTreeHead != NULL)
    {
        if (pstTreeHead->pstLeftChild != NULL)
        {
            DestroyTree(pstTreeHead->pstLeftChild);
        }

        if (pstTreeHead->pstRightChild != NULL)
        {
            DestroyTree(pstTreeHead->pstRightChild);
        }

        DestroyTreeNode(pstTreeHead);
    }
}

/* 获取树的深度 */
int GetTreeDepth(TreeHead_S *pstTreeHead)
{
    int l = 0;
    int r = 0;
    TreeNode_S *pstLeftChild;
    TreeNode_S *pstRightChild;

    if (pstTreeHead == NULL)
    {
        return 0;
    }
    l = 1;
    r = 1;


    l += GetTreeDepth(pstTreeHead->pstLeftChild);
    r += GetTreeDepth(pstTreeHead->pstRightChild);

    if (l < r)
    {
        l = r;
    }

    return l;

}

/* 前序遍历 */
void Front_Scan(TreeHead_S *pstTreeHead)
{
    if (pstTreeHead == NULL)
    {
        return;
    }

    printf("%d ",pstTreeHead->idata);
    Front_Scan(pstTreeHead->pstLeftChild);
    Front_Scan(pstTreeHead->pstRightChild);

    return;
}

/* 中序遍历 */
void Middle_Scan(TreeHead_S *pstTreeHead)
{
    if (pstTreeHead == NULL)
    {
        return;
    }

    Middle_Scan(pstTreeHead->pstLeftChild);
    printf("%d ",pstTreeHead->idata);
    Middle_Scan(pstTreeHead->pstRightChild);

    return;
}

/* 后序遍历 */
void End_Scan(TreeHead_S *pstTreeHead)
{
    if (pstTreeHead == NULL)
    {
        return;
    }

    End_Scan(pstTreeHead->pstLeftChild);
    End_Scan(pstTreeHead->pstRightChild);
    printf("%d ",pstTreeHead->idata);

    return;
}

int main(void)
{
    TreeHead_S *pstTree;
    TreeNode_S *pstNode8 = CreateTreeNode(8, NULL, NULL);
    TreeNode_S *pstNode7 = CreateTreeNode(7, NULL, NULL);
    TreeNode_S *pstNode6 = CreateTreeNode(6, NULL, NULL);
    TreeNode_S *pstNode5 = CreateTreeNode(5, NULL, NULL);
    TreeNode_S *pstNode4 = CreateTreeNode(4, pstNode8, NULL);
    TreeNode_S *pstNode3 = CreateTreeNode(3, pstNode6, pstNode7);
    TreeNode_S *pstNode2 = CreateTreeNode(2, pstNode4, pstNode5);
    TreeNode_S *pstNode1 = CreateTreeNode(1, pstNode2, pstNode3);

    assert((pstNode1 != NULL)&&(pstNode2 != NULL)&&(pstNode3 != NULL)&&
           (pstNode4 != NULL)&&(pstNode5 != NULL)&&(pstNode6 != NULL)&&
           (pstNode7 != NULL)&&(pstNode8 != NULL));

    pstTree = InitTree(pstNode1);

    printf("depth:%d\n", GetTreeDepth(pstTree));

    printf("front scan: ");
    Front_Scan(pstTree);
    printf("\nmiddle scan: ");
    Middle_Scan(pstTree);
    printf("\nend scan: ");
    End_Scan(pstTree);
    printf("\ndestroy tree: ");
    DestroyTree(pstTree);
    printf("\n");

    return 0;
}