高人相助，求一算法！！~~~~

Question

我现在坐标轴上有N个动态点存在数组里，
我鼠标点击的时候获取了一个新的点pointA，
我现在想算出pointA靠数组里的点距离近的点，

Answer 1

 List<XY> lxys = new List<XY>();
        private void Form3_Load(object sender, EventArgs e)
        {
            lxys.Add(new XY(10, 10));
            lxys.Add(new XY(200, 200));
            lxys.Add(new XY(400, 400));
            lxys.Add(new XY(800, 800));
            lxys.Add(new XY(1000, 1000));
        }        public class XY
        {
            public XY(int x, int y)
            {
                this.x = x;
                this.y = y;
            }
            private int x;
            public int X
            {
                get { return x; }
                set { x = value; }
            }
            private int y;            public int Y
            {
                get { return y; }
                set { y = value; }
            }            public int GetXY(int ex, int ey)
            {
                return Math.Abs(ex - x) + Math.Abs(ey - y);            }
        }        private void Form3_MouseDown(object sender, MouseEventArgs e)
        {
            XY lsxy = null;
            foreach (XY xy in lxys)
            {
                int x = Math.Abs(e.X - xy.X);
                int y = Math.Abs(e.Y - xy.Y);
                if (lsxy == null)
                    lsxy = xy;
                else if (lsxy.GetXY(e.X, e.Y) > x + y)
                    lsxy = xy;
            }
            MessageBox.Show("鼠标点的坐标是x:" + e.X + " y:" + e.Y + "\n\r最接近的点是 x:" + lsxy.X + " y:" + lsxy.Y);
        }

Answer 2

        private Point GetPoint(Point p)
        {
            Point pp = new Point();
            for (int i = 0; i < Pointes.Count; i++)
            {
                for (int z = 1; z < Pointes.Count; z++)
                {
                    if (Math.Sqrt(Math.Pow(Math.Abs(p.X - Pointes[i].X), 2) + Math.Pow(Math.Abs(p.Y - Pointes[i].Y), 2)) > Math.Sqrt(Math.Pow(Math.Abs(p.X - Pointes[z].X), 2) + Math.Pow(Math.Abs(p.Y - Pointes[z].Y), 2)) ? true : false)
                    {
                        pp=Pointes[z];
                    }
                    else
                    {
                        pp=Pointes[i];
                    }                }
            }
           
            return pp;
        }帮我看看有没有什么问题？