- 归并排序的非递归算法实现的算法部分学习了 归并排序三种实现方法（递归、非递归和自然合并排序） 摘片段如下：
1) 基本思想：
将数组中的相邻元素两两配对。用Merge()函数将他们排序，构成n/2组长度为2的排序好的子数组段，然后再将他们合并成长度为4的子数组段，如此继续下去，直至整个数组排好序2) 具体过程如下图所示： 例1：8 3 2 6 7 1 5 4
将算法部分实现后，用java的awt和swing实现算法的动画效果
实现的效果如下：
完整流程：
输入框输入数字
检查输入是否有除了数字和空格的非法字符
开始归并算法的非递归演示的动画 （因为屏幕大小问题，当输入个数大于16时弹出框将全屏显示，但即使如此，1920*1080的屏幕也建议输入不要超过22个，不然右边会超出屏幕不显示）
Java代码：
（因为是算法课的一个小作业，花了一天写的，用了比较多的数据结构去实现（耗费比较多空间），可能有的地方的代码不是最好的实现方式）
1.MergeSort204.java
package mergesort204;
/**
* @Author sriting.
*/
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Panel;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Stack;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
//归并排序的非递归算法
//non-recursion implementation and animation of MergeSort algorithm
public class MergeSort204 {
static node[][] matrix; //存每步merge的node //store all nodes of each step of merge
static int[][] sequence; //存上一行node的比较大小顺序 //store the comparation sequence of last step's nodes
static node[] array;
static final int width = 40;
static final int height = 30;
static final int gap = 40 ;
static int frameWidth = 1400;
static int frameHeight = 700;
static int sortf=0;
static int sorts=0;
static int splitf = 1;
static int splits = 1;
static boolean paintOnce = true;
public static void main(String args[]){
JMergeSort ms = new JMergeSort();
}
public static class JMergeSort extends JFrame{
public JMergeSort(){
//开始画输入窗口 //start to draw input window
this.setSize(600,500);
this.setLocationRelativeTo(null);
this.setLayout(new BorderLayout());
this.setTitle("MergeSort Algorithm");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel note = new JLabel(" Please enter numbers you want to \nsort and seperate each by space:");
JTextArea text = new JTextArea();
JButton button = new JButton("Start Merge");
this.add(note,BorderLayout.NORTH);
note.setFont(new Font("monspaced", Font.BOLD, 16));
note.setPreferredSize(new Dimension(450,100));
this.add(new JScrollPane(text),BorderLayout.CENTER);
text.setFont(new Font("monspaced", Font.BOLD, 18));
text.setPreferredSize(new Dimension(400,200));
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
//开始merge部分，实例化一个MergeSort204类 //start the Merge part, instantiate a MergeSort204 class
MergeSort204 mer = new MergeSort204();
//从JTextArea中提取node数组 //get array of node from JTextArea in input window
array = mer.userInput(text);
int column = 1+ (int)Math.ceil(Math.log(array.length)/Math.log(2));
matrix = new node[column][array.length];
sequence = new int[column-1][array.length];
//给matrix的第一行node赋值，注意不能直接把array[i]这个对象赋给matrix，传递的是地址不是值
//assign variables' value to nodes in first row of matrix, note that cannot assign object (address) directly to matrix
for(int i=0;i<array.length;i++){
matrix[0][i] = new node( "",0, 0);
matrix[0][i].x1 = array[i].x1;
matrix[0][i].y1 = array[i].y1;
matrix[0][i].value = array[i].value;
}
//对数组array进行merge //merge the nodes in array
mer.mergeSort(array);
//开始画动画窗口部分 //start to draw animation window
try {
Thread.sleep(500);
} catch (InterruptedException ie){}; //按完按钮0.5秒后弹出新窗口
JFrame result = new JFrame("MergeSort Animation");
if(array.length<=16){
result.setSize(frameWidth, frameHeight);
}else{
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
result.setSize(d.width, d.height);
}
result.setLocationRelativeTo(null);
MergePanel mp = new MergePanel();
mp.setBackground(Color.WHITE);
result.getContentPane();
result.add(mp);
result.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
result.setVisible(true);
}
});
button.setFont(new Font("monspaced", Font.BOLD, 20));
this.add(button, BorderLayout.SOUTH);
button.setPreferredSize(new Dimension(300,100));
this.setVisible(true);
}
}
//
public static class MergePanel extends Panel{
int x=0;int lastx=0;int lastnode;
int y=0;int lasty =0;
String nValue=null;String lastv = null;
public void paint(Graphics g){
super.paint(g);
if(paintOnce){
g.setFont(new Font("monspaced", Font.BOLD, 16)); //设置字体大小
for(int i=0; i<matrix.length;i++){
for(int j=0; j<matrix[i].length;j++){
if(i>0){
lastnode = sequence[i-1][j];
lastx = matrix[i-1][lastnode].x1;
lasty = matrix[i-1][lastnode].y1;
lastv = matrix[i-1][lastnode].value;
g.setColor(Color.RED);
g.drawRect(lastx,lasty,width,height);
g.drawString(lastv,lastx+10,lasty+20);
}
x=matrix[i][j].x1;
y=matrix[i][j].y1;
nValue = matrix[i][j].value;
g.setColor(Color.BLACK);
g.drawRect(x,y,width,height);
g.drawString(nValue,x+10,y+20);
if(i>0){
g.setColor(Color.BLUE);
g.drawLine(lastx+width/2, lasty+height, x+width/2, y);
try {
if(array.length<=16){
Thread.sleep(1000);
}else{
Thread.sleep(500);
}
} catch (InterruptedException e){}
}
}
}
}
paintOnce = false; //防止paint画两次 //avoid the paint() to automatically draw twice.
}
}
public static node[] userInput(JTextArea text){
Stack k = new Stack();
int index = 0;
String s = text.getText();
System.out.println(s);
String[] sarr = s.split("\\s+");
int testint; Stack intstack = new Stack();
for(int i=sarr.length-1; i>=0;i--){
//检查输入是否有除数字、空格以外的非法字符，把合法数字存入栈里
//check if the input has invalid symbol except digit and space, then put digit into stack
try{
testint = Integer.parseInt(sarr[i]);
intstack.push(testint);
index++;
}catch(NumberFormatException e){
System.out.println("Input has invalid text. Please enter either digital number or empty space.");
}
}
System.out.println(index+" After checking invalid symbol:");
node[] a = new node[index];
//把栈里的数字pop出来装进array里 //pop all digit and assign them to relative node's value in array
if (index > 0) {
for (int i = 0; i < index; i++) {
node p = new node( intstack.pop().toString(), (i+1)*(width+gap), gap);
a[i] = p;
System.out.print(a[i].value + " ");
}
}
return a;
}
public static void mergeSort(node[] arr){
int len = 1;int cycle=1;
//每步merege时(循环n次时），一个merge part的长度是2^(n-1)
//in each step of merge(in n times loop), the length of a merge part is 2^(n-1)
while(len < arr.length){
int num=0;
for(int i = 0; i < arr.length; i += 2*len){
merge(arr, i, len, cycle, num);
num += 2*len;
}
for(int k=0;k<arr.length;k++){
matrix[cycle][k] = new node( "",0, 0);
matrix[cycle][k].x1 = arr[k].x1;
matrix[cycle][k].y1 = 2*cycle*gap+gap;
matrix[cycle][k].value = arr[k].value;
}
System.out.println();
cycle++;
len *= 2;
}
}
public static void merge(node[] arr, int i, int len, int level,int num){
int start = i;
int len_i = i + len;//归并的前半部分数组 //first part array of merge
int j = i + len;
int len_j = j +len;//归并的后半部分数组 //second part array of merge
node[] temp = new node[2*len];
int count = 0;
//对比左右部分，每次取剩余的最小值装入temp数组
//compare value of nodes from left and right part, choose the smallest one and store to temp array each time
while(i < len_i && j < len_j && j < arr.length){
int left=Integer.parseInt(arr[i].value);
int right= Integer.parseInt(arr[j].value);
if(left<=right){
temp[count] = new node( "",0, 0);
temp[count].x1 = arr[i].x1;
temp[count].y1 = arr[i].y1;
temp[count].value = arr[i].value;
sequence[level-1][start+count]=i;
count++;i++;
}
else{
temp[count] = new node("",0, 0);
temp[count].x1 = arr[j].x1;
temp[count].y1 = arr[j].y1;
temp[count].value = arr[j].value;
sequence[level-1][start+count]=j;
count++;j++;
}
}
//当左边或右边的node先取完，把另一边的剩下的node全放进temp数组
//if nodes of left part or right part has been fully gotten, put all least nodes into temp array
while(i < len_i && i < arr.length){
temp[count] = new node( "",0, 0);
temp[count].x1 = arr[i].x1;
temp[count].y1 = arr[i].y1;
temp[count].value = arr[i].value;
sequence[level-1][start+count]=i;
count++;i++;
}
while(j < len_j && j < arr.length){
temp[count] = new node( "",0, 0);
temp[count].x1 = arr[j].x1;
temp[count].y1 = arr[j].y1;
temp[count].value = arr[j].value;
sequence[level-1][start+count]=j;
count++;j++;
}
//计算每个node的坐标x //calculate each node's coordinate X
for(int n=0;n<count;n++){
temp[n].x1 = (int)((Math.pow(2, level-1)-0.5)*gap + n*width+2*num*width);
}
count = 0;
//把temp里的node放进array对应的位置
while(start < j && start < arr.length){
arr[start].x1 = temp[count].x1;
arr[start].y1 = temp[count].y1;
arr[start].value = temp[count].value;
start++;count++;
}
}
}
2.node.java
package mergesort204;
/**
* @Author sriting.
*/
public class node {
String value;
int x1;
int y1;
node(String nodeValue, int nodeX1, int nodeY1){
value=nodeValue;
x1=nodeX1;
y1=nodeY1;
}
}
- 同时发在了我的github上：https://github.com/sriting/mergeSort204