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Prints a nicely formatted binary tree
package foo;
import java.util.ArrayList;
import java.util.List;
/**
* Binary tree printer
* Taken from http://stackoverflow.com/questions/4965335/how-to-print-binary-tree-diagram - @author MightyPork
*
*/
public class TreePrinter {
/**
* Node that can be printed
*/
public interface PrintableNode {
/**
* Get left child
*/
PrintableNode getLeft();
/**
* Get right child
*/
PrintableNode getRight();
/**
* Get text to be printed
*/
String getText();
}
/**
* Given an array of Objects
* @param elems array of integer elems
*/
public static <T> void print(T[] elems) {
Node root = getNode(elems, 0);
print(root);
}
private static <T> Node getNode(T[] elems, int index) {
final Node n;
if (index < elems.length) {
n = new Node(elems[index].toString());
n.left = getNode(elems, 2*index+1);
n.right = getNode(elems, 2*index+2);
} else {
n = null;
}
return n;
}
static class Node implements PrintableNode {
final String val;
private Node left;
private Node right;
Node(String pVal) {
this.val = pVal;
}
void setNodes(Node pLeft, Node pRight) {
left = pLeft;
right = pRight;
}
@Override
public PrintableNode getLeft() {
return left;
}
@Override
public PrintableNode getRight() {
return right;
}
@Override
public String getText() {
return val;
}
}
/**
* Print a tree
*
* @param root tree root node
*/
public static void print(PrintableNode root) {
List<List<String>> lines = new ArrayList<List<String>>();
List<PrintableNode> level = new ArrayList<PrintableNode>();
List<PrintableNode> next = new ArrayList<PrintableNode>();
level.add(root);
int nn = 1;
int widest = 0;
while (nn != 0) {
List<String> line = new ArrayList<String>();
nn = 0;
for (PrintableNode n : level) {
if (n == null) {
line.add(null);
next.add(null);
next.add(null);
} else {
String aa = n.getText();
line.add(aa);
if (aa.length() > widest) {
widest = aa.length();
}
next.add(n.getLeft());
next.add(n.getRight());
if (n.getLeft() != null) nn++;
if (n.getRight() != null) nn++;
}
}
if (widest % 2 == 1) widest++;
lines.add(line);
List<PrintableNode> tmp = level;
level = next;
next = tmp;
next.clear();
}
int perpiece = lines.get(lines.size() - 1).size() * (widest + 4);
for (int i = 0; i < lines.size(); i++) {
List<String> line = lines.get(i);
int hpw = (int) Math.floor(perpiece / 2f) - 1;
if (i > 0) {
for (int j = 0; j < line.size(); j++) {
// split node
char c = ' ';
if (j % 2 == 1) {
if (line.get(j - 1) != null) {
c = (line.get(j) != null) ? '' : '';
} else {
if (j < line.size() && line.get(j) != null) c = '';
}
}
System.out.print(c);
// lines and spaces
if (line.get(j) == null) {
for (int k = 0; k < perpiece - 1; k++) {
System.out.print(" ");
}
} else {
for (int k = 0; k < hpw; k++) {
System.out.print(j % 2 == 0 ? " " : "");
}
System.out.print(j % 2 == 0 ? "" : "");
for (int k = 0; k < hpw; k++) {
System.out.print(j % 2 == 0 ? "" : " ");
}
}
}
System.out.println();
}
// print line of numbers
for (int j = 0; j < line.size(); j++) {
String f = line.get(j);
if (f == null) f = "";
int gap1 = (int) Math.ceil(perpiece / 2f - f.length() / 2f);
int gap2 = (int) Math.floor(perpiece / 2f - f.length() / 2f);
// a number
for (int k = 0; k < gap1; k++) {
System.out.print(" ");
}
System.out.print(f);
for (int k = 0; k < gap2; k++) {
System.out.print(" ");
}
}
System.out.println();
perpiece /= 2;
}
}
}
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