创建排序二叉树

创建排序二叉树：插入时，从根开始遍历。

如果比根小，判断有没有左节点，有则向左走，没有则将该节点作为左节点。

如果比根大，判断有没有右节点，有则向右走，没有则将该节点作为右节点。

初级版代码：

Tree* Create(int * arr,int len)
{
    Tree* pRoot = (Tree*)malloc(sizeof(Tree));
    pRoot->val = arr[0];
    pRoot->pleft = NULL;
    pRoot->pright = NULL;
    for(int i = 1; i < len;i++)
    {
        Tree* tree = (Tree*)malloc(sizeof(Tree));
        tree->val = arr[i];
        tree->pleft = NULL;
        tree->pright = NULL;
        Tree* tmp = pRoot;
        while(1)
        {
            if(arr[i] == tmp->val)
                return NULL;
            else if(arr[i] < tmp->val)
                if(tmp->pleft != NULL)
                    tmp = tmp->pleft;
                else 
                    {tmp->pleft = tree;
                    break;}
            else if(arr[i] > tmp->val)
                if(tmp->pright != NULL)
                    tmp = tmp->pright;
                else
                {    tmp->pright = tree;
                break;}
        }
    }
    return pRoot;
}

升级版代码：

void InsertNode(BinaryTree **pTree,int nNum)
{
    BinaryTree *pTemp = NULL;
    pTemp = (BinaryTree*)malloc(sizeof(BinaryTree));
    pTemp->nValue = nNum;
    pTemp->pLeft = NULL;
    pTemp->pRight = NULL;
    
    //树空
    if(*pTree == NULL)
    {
        *pTree = pTemp;
        return;
    }

    BinaryTree *pNode = NULL;
    pNode = *pTree;

    while(1)
    {
        if(pNode->nValue > nNum)
        {
            //去左侧
            if(pNode->pLeft == NULL)
            {
                pNode->pLeft = pTemp;
                return;
            }

            pNode = pNode->pLeft;
        }
        else if(pNode->nValue < nNum)
        {
            //右侧
            if(pNode->pRight == NULL)
            {
                pNode->pRight = pTemp;
                return;
            }
            pNode = pNode->pRight;
        }
        else
        {
            //相等
            printf("error.\n");
            return;
        }
    }
}

BinaryTree *CreateBST(int arr[],int nLength)
{
    if(arr == NULL || nLength <=0)return NULL;
    
    BinaryTree *pTree = NULL;
    int i;
    for(i = 0;i<nLength;i++)
    {
        InsertNode(&pTree,arr[i]);
    }
    return pTree;
}