二叉树
import java.util.ArrayList;import java.util.LinkedList;import java.util.List;import java.util.Stack;public class BinaryTree<E extends Comparable<E>> extends AbstractTree<E> { private TreeNode<E> root = null; private int size = 0; @Override public boolean search(E e) { // TODO Auto-generated method stub TreeNode<E> current = root; while(current != null) { if(e.compareTo(current.item) < 0) { current = current.left; } else if(e.compareTo(current.item) > 0) { current = current.right; } else { return true; } } return false; } @Override public boolean delete(E e) { // TODO Auto-generated method stub TreeNode<E> current = root; while(current != null) { if(e.compareTo(current.item) < 0) { current = current.left; } else if(e.compareTo(current.item) > 0) { current = current.right; } else { break; } } if(current == null) { return false; } if(current.left == null) { if(current.parent == null) { root = current.right; current.right.parent = null; } else { if(e.compareTo(current.parent.item) < 0) { current.parent.left = current.right; if(current.right != null) { //必须要这个判断,否则java.lang.NullPointerException current.right.parent = current.parent.left; } //help GC current.parent = null; current.right = null; current = null; } else { current.parent.right = current.right; if(current.right != null) { //必须要这个判断,否则java.lang.NullPointerException current.right.parent = current.parent.right; } //help GC current.parent = null; current.right = null; current = null; } } } else { TreeNode<E> rm = current.left; while(rm.right != null) { rm = rm.right; } current.item = rm.item; if(rm.parent.right == rm) { rm.parent.right = rm.left; if(rm.left != null) { //必须要这个判断,否则java.lang.NullPointerException rm.left.parent = rm.parent; } //help GC rm.item = null; rm.left = null; rm = null; } else { current.left = rm.left; if(rm.left != null) { //必须要这个判断,否则java.lang.NullPointerException rm.left.parent = current; } //help GC rm.item = null; rm.left = null; rm = null; } } size--; return true; } @Override public boolean insert(E e) { // TODO Auto-generated method stub if(root == null) { root = new TreeNode<E>(e); size++; } else { TreeNode<E> parent = null; TreeNode<E> current = root; while(current != null) { if(e.compareTo(current.item) < 0) { parent = current; current = current.left; } else if(e.compareTo(current.item) > 0) { parent = current; current = current.right; } else { return false; } } if(e.compareTo(parent.item) < 0) { parent.left = new TreeNode<E>(e); parent.left.parent = parent; } else { parent.right = new TreeNode<E>(e); parent.right.parent = parent; } size++; } return true; } @Override public void inorder() { // TODO Auto-generated method stub inorder(root); } private void inorder(TreeNode<E> root) { if(root == null) { return ; } inorder(root.left); System.out.print(root.item + " "); inorder(root.right); } @Override public void nrinorder() { // TODO Auto-generated method stub Stack<TreeNode<E>> stack = new Stack<>(); TreeNode<E> c = root; while(!stack.isEmpty() || c!=null) { while(c != null) { stack.push(c); c = c.left; } c = stack.pop(); System.out.print(c.item + " "); c = c.right; } } @Override public void preorder() { // TODO Auto-generated method stub preorder(root); } private void preorder(TreeNode<E> root) { // TODO Auto-generated method stub if(root == null) { return; } System.out.print(root.item + " "); preorder(root.left); preorder(root.right); } @Override public void nrpreorder() { // TODO Auto-generated method stub TreeNode<E> current = root; Stack<TreeNode<E>> stack = new Stack<>(); while(!stack.isEmpty() || current!=null) { if(current == null) { current = stack.pop(); } System.out.print(current.item + " "); if(current.right != null) { stack.push(current.right); } current = current.left; } } @Override public void postorder() { // TODO Auto-generated method stub postorder(root); } private void postorder(TreeNode<E> root) { if(root == null) { return; } postorder(root.left); postorder(root.right); System.out.print(root.item + " "); } @Override public void nrpostorder() { // TODO Auto-generated method stub TreeNode<E> last = null; TreeNode<E> current = root; Stack<TreeNode<E>> stack = new Stack<>(); while(!stack.isEmpty() || current!=null) { while(current != null) { stack.push(current); current = current.left; } current = stack.peek(); if(current.right==null || current.right==last) { System.out.print(current.item + " "); last = stack.pop(); current = null; } else { current = current.right; } } } @Override public void breadthorder() { // TODO Auto-generated method stub LinkedList<TreeNode<E>> list = new LinkedList<>(); TreeNode<E> current = root; list.add(current); int index = 0; while(index < getSize()) { for(int i=0;i<list.size();i++) { if(list.get(i) != null) { TreeNode<E> temp = list.get(i); System.out.print(temp.item + " "); list.add(i, temp.left); list.add(i+1,temp.right); list.remove(temp); index++; i++; } } } } @Override public int getSize() { // TODO Auto-generated method stub return size; } @Override public void clear() { // TODO Auto-generated method stub clearPreorder(root); size = 0; } private void clearPreorder(TreeNode<E> root) { root.parent = null; root.item = null; clearPreorder(root.left); clearPreorder(root.right); } //获得指定元素的路径,如果二叉树中不存在此元素,则返回null public ArrayList<TreeNode<E>> path(E e) { if(!search(e)) { return null; } ArrayList<TreeNode<E>> list = new ArrayList<>(); TreeNode<E> current = root; while(current != null) { list.add(current); if(e.compareTo(current.item) < 0) { current = current.left; } else if(e.compareTo(current.item) > 0) { current = current.right; } else { break; } } return list; } //返回二叉树的高度 public int height() { int len = 0; ArrayList<TreeNode<E>> list = new ArrayList<>(); TreeNode<E> current = root; list.add(current); int index = 0; while(index < getSize()) { for(int i=0;i<list.size();i++) { if(list.get(i) != null) { TreeNode<E> temp = list.get(i); list.add(i, temp.left); list.add(i+1, temp.right); list.remove(temp); index++; i++; } } len++; } return len; } //如果此二叉树为完全二叉树,则返回true public boolean isFullBinaryTree() { ArrayList<TreeNode<E>> list = new ArrayList<>(); TreeNode<E> current = root; list.add(current); int index = 0; while(index < getSize()) { for(int i=0;i<list.size();i++) { if(list.get(i) != null) { TreeNode<E> temp = list.get(i); list.add(i,temp.left); list.add(i+1,temp.right); list.remove(temp); index++; i++; } else { return false; } } } return true; } //返回根节点 public TreeNode<E> getRoot() { return root; } //返回指定元素的父节点 public TreeNode<E> getParent(E e) { TreeNode<E> current = root; while(current != null) { if(e.compareTo(current.item) < 0) { current = current.left; } else if(e.compareTo(current.item) > 0) { current = current.right; } else { return current.parent; } } return null; } //返回叶子节点的个数 public int getNumberOfLeaves() { return getNumberOfLeaves(root); } private int getNumberOfLeaves(TreeNode<E> root) { if(root == null) { return 0; } else if(root.right==null && root.left==null) { return 1; } else { return getNumberOfLeaves(root.left) + getNumberOfLeaves(root.right); } } //返回非叶子节点的个数 public int getNumberOfNonLeaves() { return getSize()-getNumberOfLeaves(); } static class TreeNode<E extends Comparable<E>> { protected E item; protected TreeNode<E> parent; protected TreeNode<E> left; protected TreeNode<E> right; public TreeNode(E item) { this.item = item; } }}
