java 常见排序算法的实现 包括二叉树

/** * 二叉树测试二叉树顺序存储在treeLine中，递归前序创建二叉树。另外还有能 * 够前序、中序、后序、按层遍历二叉树的方法以及一个返回遍历结果asString的 * 方法。 */ public class BitTree { public static Node2 root; public static String asString; //事先存入的数组,符号#表示二叉树结束。 public static final char[] treeLine = {'a','b','c','d','e','f','g',' ',' ','j',' ',' ','i','#'}; //用于标志二叉树节点在数组中的存储位置，以便在创建二叉树时能够找到节点对应的数据。 static int index; //构造函数 public BitTree() { System.out.print("测试二叉树的顺序表示为："); System.out.println(treeLine); this.index = 0; root = this.setup(root); } //创建二叉树的递归程序 private Node2 setup(Node2 current) { if (index >= treeLine.length) return current; if (treeLine[index] == '#') return current; if (treeLine[index] == ' ') return current; current = new Node2(treeLine[index]); index = index * 2 + 1; current.left = setup(current.left); index ++; current.right = setup(current.right); index = index / 2 - 1; return current; } //二叉树是否为空。 public boolean isEmpty() { if (root == null) return true; return false; } //返回遍历二叉树所得到的字符串。 public String toString(int type) { if (type == 0) { asString = "前序遍历：\t"; this.front(root); } if (type == 1) { asString = "中序遍历：\t"; this.middle(root); } if (type == 2) { asString = "后序遍历：\t"; this.rear(root); } if (type == 3) { asString = "按层遍历：\t"; this.level(root); } return asString; } //前序遍历二叉树的循环算法，每到一个结点先输出，再压栈，然后访问它的左子树， //出栈，访问其右子树，然后该次循环结束。 private void front(Node2 current) { StackL stack = new StackL((Object)current); do { if (current == null) { current = (Node2)stack.pop(); current = current.right; } else { asString += current.ch; current = current.left; } if (!(current == null)) stack.push((Object)current); } while (!(stack.isEmpty())); } //中序遍历二叉树 private void middle(Node2 current) { if (current == null) return; middle(current.left); asString += current.ch; middle(current.right); } //后序遍历二叉树的递归算法 private void rear(Node2 current) { if (current == null) return; rear(current.left); rear(current.right); asString += current.ch; } } /** * 二叉树所使用的节点类。包括一个值域两个链域 */ public class Node2 { char ch; Node2 left; Node2 right; //构造函数 public Node2(char c) { this.ch = c; this.left = null; this.right = null; } //设置节点的值 public void setChar(char c) { this.ch = c; } //返回节点的值 public char getChar() { return ch; } //设置节点的左孩子 public void setLeft(Node2 left) { this.left = left; } //设置节点的右孩子 public void setRight (Node2 right) { this.right = right; } //如果是叶节点返回true public boolean isLeaf() { if ((this.left == null) && (this.right == null)) return true; return false; } }