/// <summary>
/// 将节点按距离插入列表中
/// </summary>
/// <param name="list"></param>
/// <param name="k"></param>
/// <param name="bbf"></param>
private void insert(List <BBFData> list, int k, BBFData bbf)
{
if (list.Count == 0)
{
list.Add(bbf);
return;
}
int ret = 0;
int oldCount = list.Count;
var last = list[list.Count - 1];
var df = bbf.d;
var dn = last.d;
if (df >= dn) // bbf will be appended to list
{
if (oldCount == k) // already has k nearest neighbors, nothing should be done
{
return;
}
list.Add(bbf); // append directively
return;
}
// bbf will be inserted into list internally
if (oldCount < k)
{
// suppose bbf be inserted at idx1, all elements after idx1 should be moved 1 backward respectively
// first we move the last element
list.Add(last);
}
// from backer to former, move related elements
int i = oldCount - 2;
while (i > -1)
{
if (list[i].d <= df)
{
break;
}
list[i + 1] = list[i]; // move backward
i--;
}
i++;
list[i] = bbf;
}
/// <summary>
/// 搜索k近邻点
/// </summary>
/// <param name="p"></param>
/// <param name="k"></param>
/// <returns></returns>
public List <TreeNode> BBFSearchKNearest(Point p, int k)
{
var list = new List <BBFData>(); //
var pq = new MinPQ();
pq.insert(new PQNode(root, 0));
int t = 0;
while (pq.nodes.Count > 0 && t < max_nn_chks)
{
var expl = pq.pop_min_default().data;
expl = Explore2Leaf(expl, p, pq);
var bbf = new BBFData(expl, expl.point.Distance(p));
insert(list, k, bbf);
t++;
}
return(list.Select(l => l.data).ToList());
}
