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二叉搜索树
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‎src/cn/edu/tju/rico/BinarySearchTree/BinarySearchTree.java‎

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package cn.edu.tju.rico.BinarySearchTree;
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public class BinarySearchTree {
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private TreeNode root;
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/**
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* @description 根据已知序列构建二叉搜索树
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* @author rico
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* @created 2017年6月3日 下午6:15:54
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* @param input
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*/
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public BinarySearchTree(int[] input) {
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createBinarySearchTree(input);
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}
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/**
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* @description 根据已知序列构建二叉搜索树
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* @author rico
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* @created 2017年6月3日 下午6:15:06
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* @param input
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*/
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public void createBinarySearchTree(int[] input) {
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if (input != null) {
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for (int i = 0; i < input.length; i++) {
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root = insert(input[i], root);
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}
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}
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}
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/**
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* @description 二叉搜索树的搜索算法，递归算法
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* @author rico
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* @created 2017年6月3日 下午3:27:43
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* @param target
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* 目标值
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* @param root
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* 二叉搜索树的根结点
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* @return
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*/
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public TreeNode search(int target, TreeNode root) {
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TreeNode result = null;
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if (root != null) { // 递归终止条件
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if (target == root.data) { // 递归终止条件
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result = root;
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return result;
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} else if (target < root.data) { // 目标值小于根结点值，从左子树查找
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result = search(target, root.left);
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} else { // 目标值大于根结点值，从右子树查找
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result = search(target, root.right);
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}
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}
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return result;
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}
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/**
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* @description 二叉搜索树的插入操作
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* @author rico
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* @created 2017年6月3日 下午5:55:05
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* @param target
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* @param node
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* @return
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*/
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public TreeNode insert(int target, TreeNode node) {
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if (search(target, node) == null) {
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if (node == null) {
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return new TreeNode(target);
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} else {
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if (target < node.data) {
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node.left = insert(target, node.left);
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} else {
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node.right = insert(target, node.right);
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}
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}
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}
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return node;
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}
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/**
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* @description 删除搜索二叉树的制定结点
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* @author rico
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* @created 2017年6月3日 下午8:43:29
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* @param target
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* @param node
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* @return
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*/
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public TreeNode remove(int target, TreeNode node) {
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TreeNode tmp = null;
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if (node != null) {
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if (target < node.data) { // 从左子树删除
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node.left = remove(target, node.left);
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} else if (target > node.data) { // 从右子树删除
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node.right = remove(target, node.right);
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} else if (node.left != null && node.right != null) { // 找到待删除结点，且其左右子树不为空
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// 找到以待删除结点右子树的中序遍历第一个结点(最小结点)
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tmp = node.right;
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while (tmp.left != null) {
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tmp = tmp.left;
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}
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// 用最小结点补位待删除结点
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node.data = tmp.data;
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// 删除待删除结点右子树上补位结点
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node.right = remove(node.data, node.right);
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} else {
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if (node.left == null) {
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node = node.right;
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} else {
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node = node.left;
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}
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}
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}
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return node;
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}
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/**
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* @description 中序遍历二叉搜索树，递归算法，升序排序
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* @author rico
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* @created 2017年6月3日 下午3:52:54
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* @param root
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*/
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public void inOrder(TreeNode node) {
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if (node != null) {
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inOrder(node.left);
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System.out.print(root.data + " ");
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inOrder(node.right);
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}
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}
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/**
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* @description 打印二叉搜索树
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* @author rico
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* @created 2017年6月3日 下午6:08:42
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* @param node
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*/
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public void printTree(TreeNode node) {
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if (node != null) {
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System.out.print(node.data);
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if (node.left != null || node.right != null) {
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System.out.print("(");
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printTree(node.left);
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System.out.print(",");
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printTree(node.right);
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System.out.print(")");
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}
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}
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}
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/**
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* @description 访问二叉搜索树的根结点
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* @author rico
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* @created 2017年6月3日 下午3:54:49
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* @return
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*/
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public TreeNode getRoot() {
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return root;
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}
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}

‎src/cn/edu/tju/rico/BinarySearchTree/TreeNode.java‎

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package cn.edu.tju.rico.BinarySearchTree;
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public class TreeNode {
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public int data;
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public TreeNode left;
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public TreeNode right;
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public TreeNode(int data){
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this.data = data;
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}
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@Override
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public String toString() {
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return "TreeNode [data=" + data + "]";
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}
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}

‎src/cn/edu/tju/rico/backtrack/EightQueen.java‎

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package cn.edu.tju.rico.backtrack;
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import java.util.Arrays;
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import java.util.Date;
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/**
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* Title: 八皇后问题(递归算法) Description: 在8×8格的国际象棋上摆放八个皇后，使其不能互相攻击，
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* 即任意两个皇后都不能处于同一行、同一列或同一斜线上，问有多少种摆法。
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*
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* @author rico
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* @created 2017年5月31日 下午4:54:17
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*/
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public class EightQueen {
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private static final short N = 8; // 使用常量来定义，方便之后解N皇后问题
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private static int count = 0; // 结果计数器
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public static void main(String[] args) {
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Date begin = new Date();
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// 初始化棋盘，全部置0
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short chess[][] = new short[N][N];
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for (int i = 0; i < N; i++) {
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for (int j = 0; j < N; j++) {
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chess[i][j] = 0;
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}
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}
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putQueenAtRow(chess, 0);
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Date end = new Date();
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System.out.println("解决 " + N + " 皇后问题，用时："
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+ String.valueOf(end.getTime() - begin.getTime()) + "毫秒，计算结果："
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+ count);
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}
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private static void putQueenAtRow(short[][] chess, int row) {
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// 递归终止判断：如果row==N，则说明已经成功摆放了8个皇后 输出结果，终止递归
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if (row == N) {
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count++;
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System.out.println("第 " + count + " 种解：");
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for (int i = 0; i < N; i++) {
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for (int j = 0; j < N; j++) {
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System.out.print(chess[i][j] + " ");
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}
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System.out.println();
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}
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return;
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}
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short[][] chessTemp = chess.clone();
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/**
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* 向这一行的每一个位置尝试排放皇后 然后检测状态，如果安全则继续执行递归函数摆放下一行皇后
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*/
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for (int i = 0; i < N; i++) {
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// 摆放这一行的皇后，之前要清掉所有这一行摆放的记录，防止污染棋盘
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for (int j = 0; j < N; j++)
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chessTemp[row][j] = 0;
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chessTemp[row][i] = 1;
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if (isSafety(chessTemp, row, i)) {
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putQueenAtRow(chessTemp, row + 1);
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// System.out.println("-----------");
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// for (int k = 0; k < N; k++) {
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// for (int j = 0; j < N; j++) {
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// System.out.print(chess[k][j] + " ");
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// }
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// System.out.println();
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// }
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}
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}
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}
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private static boolean isSafety(short[][] chess, int row, int col) {
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// 判断中上、左上、右上是否安全
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int step = 1;
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while (row - step >= 0) {
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if (chess[row - step][col] == 1) // 中上
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return false;
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if (col - step >= 0 && chess[row - step][col - step] == 1) // 左上
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return false;
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if (col + step < N && chess[row - step][col + step] == 1) // 右上
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return false;
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step++;
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}
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return true;
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}
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}

‎src/cn/edu/tju/rico/sort/QuickSort_PartitionOnly.java‎

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package cn.edu.tju.rico.sort;
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import java.util.Arrays;
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/**
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* Title:快速排序的变形
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* Description: 本质上不断调用经典快排的划分算法
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* 时间复杂度：O(n^2)
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* @author rico
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* @created 2017年6月2日 下午9:10:43
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*/
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public class QuickSort_PartitionOnly {
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/**
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* @description 依次以数组中的每个元素为基准点进行划分，
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* 直到遍历所有元素都
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* @author rico
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* @param array
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*/
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public void quicksort(int[] array) {
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if (array != null && array.length != 0) {
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for (int i = 0; i < array.length; i++) {
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// 以下是快排的划分算法
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int base_index = 0;
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int base = array[i];
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base_index = i;
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for (int j = i+1; j < array.length; j++) {
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if (array[j] <= base ) {
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base_index ++;
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if (base_index != j) {
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int temp = array[base_index];
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array[base_index] = array[j];
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array[j] = temp;
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}
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}
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}
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array[i] = array[base_index];
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array[base_index] = base;
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System.out.println(Arrays.toString(array));
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}
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}
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}
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public static void main(String[] args) {
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// int[] array = { 1, 2, 3, 2, 2, 2, 5, 4, 2 };
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int[] array = { 1, 2, 3, 5, 0, 4, 9, 2, 6 };
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new QuickSort_PartitionOnly().quicksort(array);
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}
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}

‎src/cn/edu/tju/rico/test/BinarySearchTreeTest.java‎

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package cn.edu.tju.rico.test;
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import cn.edu.tju.rico.BinarySearchTree.BinarySearchTree;
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public class BinarySearchTreeTest {
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public static void main(String[] args) {
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int[] input = {53,78,65,17,87,9,81,45,23};
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BinarySearchTree tree = new BinarySearchTree(input);
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System.out.println("中序遍历二叉搜索树：");
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tree.inOrder(tree.getRoot());
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System.out.println();
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System.out.println("\n------------------------\n");
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System.out.println("打印二叉搜索树：");
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tree.printTree(tree.getRoot());
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System.out.println();
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System.out.println("\n------------------------\n");
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System.out.println("二叉搜索树搜索目标值：");
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System.out.println(tree.search(23, tree.getRoot()));
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System.out.println("\n------------------------\n");
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System.out.println("向二叉搜索树插入目标值：");
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tree.insert(10, tree.getRoot());
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tree.printTree(tree.getRoot());
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System.out.println();
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System.out.println("\n------------------------\n");
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System.out.println("向二叉搜索树删除目标值：");
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tree.remove(78, tree.getRoot());
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tree.printTree(tree.getRoot());
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System.out.println();
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System.out.println("\n------------------------\n");
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}
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}

‎src/cn/edu/tju/rico/test/SortTest.java‎

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System.out.println("\n----------------------\n");
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System.out.println("希尔排序 ： ");
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int[] target7 = { 21, 25, 49, 25, 16, 8, 31, 41 };
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int[] target7 = { 21, 25, 49, 25, 16, 8, 31, 41,1,16 };
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System.out.println("原数组 ： " + Arrays.toString(target7));
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ShellSort.shellSort(target7);
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System.out.println(Arrays.toString(target7));

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