3.2.38

3.2.38 #

解答 #

通过层序遍历计算结点的坐标，然后绘制即可。

先算出最大深度，确定每一层的高度 Y，

再将每一层的宽度分成 $2^n-1$ 份，从左到右依次对结点赋值。

效果如下：

代码 #

计算坐标的函数。

public void DrawTree(Graphics pen, RectangleF panel)
{
    var depth = Depth(root); // 确定最大深度。
    var layerHeight = panel.Height / depth;
    var nowLayer = new Queue<Node>();
    var nextLayer = new Queue<Node>();
    nextLayer.Enqueue(root);

    for (var layer = 0; layer != depth; layer++)
    {
        var unitSizeX = (float)(panel.Width / Math.Pow(2, layer));
        var temp = nowLayer;
        nowLayer = nextLayer;
        nextLayer = temp;

        var cursorX = 0.0f;
        var cursorY = layer * layerHeight;
        while (nowLayer.Count != 0)
        {
            var node = nowLayer.Dequeue();

            if (node != null)
            {
                nextLayer.Enqueue(node.Left);
                nextLayer.Enqueue(node.Right);
            }
            else
            {
                nextLayer.Enqueue(null);
                nextLayer.Enqueue(null);
            }


            if (node != null)
            {
                node.X = cursorX + unitSizeX / 2.0f;
                node.Y = cursorY;
            }
            
            cursorX += unitSizeX;
        }
    }
}