二叉搜索树的操作集

插入（二叉搜索树性质是左子树全小，右子树全大）：

BinTree Insert(BinTree BST, ElementType X) {
    BinTree p = BST;
    if (!p) {
        BST = (BinTree)malloc(sizeof(struct TNode));
        BST->Data = X;
        BST->Left = BST->Right = NULL;
        return BST;
    }
    BinTree temp;
    int k;
    while (p) {
        temp = p;
        if (X > p->Data) {
            p = p->Right;
            k = 0;
        }
        else {
            p = p->Left;
            k = 1;
        }
    }
    p = (BinTree)malloc(sizeof(struct TNode));
    p->Data = X;
    p->Left = p->Right = NULL;
    if (k)
        temp->Left = p;
    else
        temp->Right = p;
    return BST;
}

注意这里要记录结点存放的位置（是父结点的左孩子还是右孩子）。

查找：

Position Find(BinTree BST, ElementType X) {
    BinTree p = BST;
    while (p) {
        if (p->Data == X) {
            return p;
        }
        else if (X > p->Data) {
            p = p->Right;
        }
        else {
            p = p->Left;
        }
    }
    return NULL;
}

查找最小/大的结点（一定在二叉搜索树的最左/右叶子结点）：

Position FindMin(BinTree BST) {
    BinTree p = BST;
    if (!p)
        return p;
    BinTree temp;
    while (p) {
        temp = p;
        p = p->Left;
    }
    return temp;
}
Position FindMax(BinTree BST) {
    BinTree p = BST;
    if (!p)
        return p;
    BinTree temp;
    while (p) {
        temp = p;
        p = p->Right;
    }
    return temp;
}

删除：

BinTree Delete(BinTree BST, ElementType X) {
    if (!BST) {
        printf("Not Found
");
        return BST;
    }
    BinTree insert;
    BinTree temp;
    if (X == BST->Data) {
        if (BST->Left && BST->Right) {
            temp = BST->Left;
            BST = BST->Right;
            insert = FindMin(BST);
            if(insert)
                insert->Left = temp;
            return BST;
        }
        if (BST->Left)
            return BST->Left;
        else
            return BST->Right;
    }
    BinTree p = BST;
    temp = p;
    int k;
    if (X > p->Data) {
        p = p->Right;
        k = 0;
    }
    else {
        p = p->Left;
        k = 1;
    }
    while (p) {
        if (p->Data == X) {
            if (k) {
                if (p->Left && p->Right) {
                    temp->Left = p->Left;
                    insert = FindMax(p->Left);
                    insert->Right = p->Right;
                }
                else if (p->Left)
                    temp->Left = p->Left;
                else if (p->Right)
                    temp->Left = p->Right;
                else
                    temp->Left = NULL;
            }
            else {
                if (p->Left && p->Right) {
                    temp->Right = p->Right;
                    insert = FindMin(p->Right);
                    insert->Left = p->Left;
                }
                else if (p->Left)
                    temp->Right = p->Left;
                else if (p->Right)
                    temp->Right = p->Right;
                else
                    temp->Right = NULL;
            }
            return BST;
        }
        else if (X > p->Data) {
            p = p->Right;
            if (k)
                temp = temp->Left;
            else
                temp = temp->Right;
            k = 0;
        }
        else {
            p = p->Left;
            if (k)
                temp = temp->Left;
            else
                temp = temp->Right;
            k = 1;
        }
    }
    printf("Not Found
");
    return BST;
}