/// <summary>
/// 这是最简单的插入，没有节省空间，
/// 如果一个节点的孩子数是2，除非关键字在这个节点的范围内，否则基本不会在往这里插入节点
/// </summary>
/// <param name="value"></param>
/// <param name="tree"></param>
/// <returns></returns>
private IBNode Insert(int value, IBNode tree)
{
//说明空
if (tree == null)
{
BLeaf leaf = new BLeaf(M);
leaf.AddValue(value);
tree = leaf;
}
else if (tree.IsLeaf())
{
tree = InsertLeaf(value, tree);
}
else//递归去找叶子节点
{
var node = (BNode)tree;
bool finded = false;
for (int i = 0; i < node.Keys.Count; i++)
{
if (value < node.Keys[i])
{
tree = Insert(value, node.Children[i]);
}
}
if (!finded)
{
tree = Insert(value, node.Children[node.Keys.Count]);
}
}
return(tree);
}
private IBNode DeleteLeaf(int value, IBNode tree)
{
BLeaf leaf = (BLeaf)tree;
bool res = leaf.RemoveValue(value);
if (res)
{
if (leaf.GetChildrenNum() < Math.Ceiling(M / 2m))
{
BNode parent = leaf.Parent;
if (parent == null)
{
}
else
{
//先找到孩子节点
var siblings = parent.GetSiblings(leaf);
if (siblings.Count == 0)
{//非孩子节点
//do nothing
}
else
{
IBNode sibling = null;
foreach (var node in siblings)
{
if (node.GetChildrenNum() > Math.Ceiling(M / 2m))
{
sibling = node;
break;
}
}
if (sibling == null)
{//兄弟节点都没有多的元素
MergeLeaf((BLeaf)siblings[0], leaf);
//开始检索上级
parent = (BNode)DeleteNode(parent);
}
else
{
ShareLeafValue((BLeaf)sibling, leaf);
}
}
}
}
else
{//do nothing
}
}
else
{//节点不存在
}
return(tree);
}
private void ShareLeafValue(BLeaf leftLeaf, BLeaf rightLeaf)
{
int value = 0;
if (leftLeaf.GetMinKey() < rightLeaf.GetMinKey())
{
int i = leftLeaf.GetChildrenNum() - 1;
value = leftLeaf.Values[i];
}
else
{
value = leftLeaf.GetMinKey();
}
rightLeaf.AddValue(value);
leftLeaf.RemoveValue(value);
}
private void MergeLeaf(BLeaf leftLeaf, BLeaf rightLeaf)
{
BLeaf newLeaf = new BLeaf(M);
//位置调换一下
if (leftLeaf.GetMinKey() > rightLeaf.GetMinKey())
{
var temp = leftLeaf;
leftLeaf = rightLeaf;
rightLeaf = temp;
}
var list = leftLeaf.Values;
list.AddRange(rightLeaf.Values);
leftLeaf.Values = list;
leftLeaf.NextLeaf = rightLeaf.NextLeaf;
var parent = leftLeaf.Parent;
parent.RemoveChildren(rightLeaf);
}
private void SplitLeaf(ref BLeaf oldLeaf, out BLeaf newLeaf, int value)
{
newLeaf = new BLeaf(M);
var list = new List <int>(oldLeaf.Values);
list.Add(value);
list.Sort();
int count = list.Count;
var list1 = list.GetRange(0, count / 2);
var list2 = list.GetRange(count / 2, count - count / 2);
oldLeaf.Values = list1;
newLeaf.Values = list2;
//把叶子连起来
newLeaf.NextLeaf = oldLeaf.NextLeaf;
newLeaf.PrevLeaf = oldLeaf;
oldLeaf.NextLeaf = newLeaf;
// newLeaf.Parent = oldLeaf.Parent;
// oldLeaf.Parent.AddKey(list2[0]);
}