蓝桥杯决赛-----显示二叉树

标题：显示二叉树

排序二叉树的特征是：
某个节点的左子树的所有节点值都不大于本节点值。
某个节点的右子树的所有节点值都不小于本节点值。

为了能形象地观察二叉树的建立过程，小明写了一段程序来显示出二叉树的结构来。

class BiTree
{
private int v;
private BiTree l;
private BiTree r;

public BiTree(int v){
    this.v = v;
}

public void add(BiTree the){
    if(the.v < v){
        if(l==null) l = the;
        else l.add(the);
    }
    else{
        if(r==null) r = the;
        else r.add(the);
    }
}

public int getHeight(){
    int h = 2;
    int hl = l==null? 0 : l.getHeight();
    int hr = r==null? 0 : r.getHeight();
    return h + Math.max(hl,hr);
}

public int getWidth(){
    int w = (""+v).length();
    if(l!=null) w += l.getWidth();
    if(r!=null) w += r.getWidth();
    return w;
}

public void show(){
    char[][] buf = new char[getHeight()][getWidth()];
    printInBuf(buf, 0, 0);
    showBuf(buf);
}

private void showBuf(char[][] x){
    for(int i=0; i<x.length; i++){
        for(int j=0; j<x[i].length; j++)
            System.out.print(x[i][j]==0? ' ':x[i][j]);
        System.out.println();
    }
}

private void printInBuf(char[][] buf, int x, int y){
    String sv = "" + v;

    int p1 = l==null? x : l.getRootPos(x);
    int p2 = getRootPos(x);
    int p3 = r==null? p2 : r.getRootPos(p2+sv.length());

    buf[y][p2] = '|';
    for(int i=p1; i<=p3; i++) buf[y+1][i]='-';
    for(int i=0; i<sv.length(); i++) ________________________________;  //填空位置
    if(p1<p2) buf[y+1][p1] = '/';
    if(p3>p2) buf[y+1][p3] = '\\';

    if(l!=null) l.printInBuf(buf,x,y+2);
    if(r!=null) r.printInBuf(buf,p2+sv.length(),y+2);
}

private int getRootPos(int x){
    return l==null? x : x + l.getWidth();
}

}

public class Main
{
public static void main(String[] args)
{
BiTree tree = new BiTree(500);
tree.add(new BiTree(200));
tree.add(new BiTree(509));
tree.add(new BiTree(100));
tree.add(new BiTree(250));
tree.add(new BiTree(507));
tree.add(new BiTree(600));
tree.add(new BiTree(650));
tree.add(new BiTree(450));
tree.add(new BiTree(510));
tree.add(new BiTree(440));
tree.add(new BiTree(220));
tree.show();
}
}

对于上边的测试数据，应该显示出：
|
/————–500—\
| |
/–200—\ /–509—\
| | | |
100 /–250—\ 507 /–600\
| | | |
220 /–450 510 650
|
440

（如有对齐问题，请参考【图1.png】）

请分析程序逻辑，填写划线部分缺失的代码。

注意，只填写缺少的部分，不要填写已有的代码或符号，也不要加任何说明文字。

package 蓝桥杯;

public class BiTree {

    private int v;
    private BiTree l;
    private BiTree r;

    public BiTree(int v){
        this.v = v;
    }

    public void add(BiTree the){
        if(the.v < v){
            if(l==null) l = the;
            else l.add(the);
        }
        else{
            if(r==null) r = the;
            else r.add(the);
        }
    }

    public int getHeight(){
        int h = 2;
        int hl = l==null? 0 : l.getHeight();
        int hr = r==null? 0 : r.getHeight();
        return h + Math.max(hl,hr);
    }

    public int getWidth(){
        int w = (""+v).length();
        if(l!=null) w += l.getWidth();
        if(r!=null) w += r.getWidth();
        return w;
    }

    public void show(){
        char[][] buf = new char[getHeight()][getWidth()];
        printInBuf(buf, 0, 0);
        showBuf(buf);
    }

    private void showBuf(char[][] x){
        for(int i=0; i<x.length; i++){
            for(int j=0; j<x[i].length; j++)
                System.out.print(x[i][j]==0? ' ':x[i][j]);
            System.out.println();
        }
    }

    private void printInBuf(char[][] buf, int x, int y){
        String sv = "" + v;
        //System.out.println(sv);
        ///左中右的位置
        int p1 = l==null? x : l.getRootPos(x);
        int p2 = getRootPos(x);
        int p3 = r==null? p2 : r.getRootPos(p2+sv.length());

        buf[y][p2] = '|';
        for(int i=p1; i<=p3; i++) buf[y+1][i]='-';
        for(int i=0; i<sv.length(); i++)  buf[y+1][p2+i] = sv.charAt(i); //填空位置
        if(p1<p2) buf[y+1][p1] = '/';
        if(p3>p2) buf[y+1][p3] = '\\';

        if(l!=null) l.printInBuf(buf,x,y+2);
        if(r!=null) r.printInBuf(buf,p2+sv.length(),y+2);
    }

    private int getRootPos(int x){
        return l==null? x : x + l.getWidth();
    }
    public static void main(String[] args)
    {       
        BiTree tree = new BiTree(500);
        tree.add(new BiTree(200));
        tree.add(new BiTree(509));
        tree.add(new BiTree(100));
        tree.add(new BiTree(250));
        tree.add(new BiTree(507));
        tree.add(new BiTree(600));
        tree.add(new BiTree(650));
        tree.add(new BiTree(450));
        tree.add(new BiTree(510));
        tree.add(new BiTree(440));
        tree.add(new BiTree(220));      
        tree.show();        
    }





}