CODE

public class Solution {
  public int[][] KClosest(int[][] points, int k) {
    List<List<int>> queue = new List<List<int>>();
    List<double> distances = new List<double>();

    for (int i = 0; i < points.Length; i++)
    {
      List<int> point = new List<int>();
      point.Add(points[i][0]); point.Add(points[i][1]);
      double distToOrigin = Math.Sqrt(points[i][0]*points[i][0] + 
                                        points[i][1]*points[i][1]);
      if (i == 0 || distToOrigin < distances[0])
      {
        queue.Insert(0,point);
        distances.Insert(0,distToOrigin);
      }
      else
      {
        int j = 0;
        while (j < distances.Count)
        {
          if (distances[j] <= distToOrigin) {j++; continue;}
          else break;
        }
        if (j > distances.Count-1) 
        {
            queue.Add(point); 
            distances.Add(distToOrigin);
        }
        else
        {
            queue.Insert(j,point);
            distances.Insert(j,distToOrigin);
        }
      }
    } 
    List<List<int>> res = new List<List<int>>();
    for (int i = 0; i < k; i++)
      res.Add(queue[i]);
    int[][] result = new int[res.Count][];
    for (int i = 0; i < res.Count; i++)
      result[i] = res[i].ToArray();
    return result;        
  }
}