Java 中序式轉後序式

import java.util.*;

public class Postfix{
    public static int priority(String str){
        switch( str ){
            case "+": case "-": 
                return 1;
            case "*": case"/": case "%": 
                return 2;
            default: 
                return 0;
        }
    }

    public static String toPostfix(String str){
        StringBuffer sb = new StringBuffer();
        LinkedList<String> stack = new LinkedList<String>();
        for(String sub : str.split(" ") ){
            if("(".indexOf(sub) != -1){
                stack.add(sub);
            }else if("+-*/%".indexOf(sub) != -1){
                while(!stack.isEmpty() && priority(stack.getLast()) >= priority(sub)){
                    sb.append(stack.removeLast() + " ");
                }
                stack.add(sub);
            }else if(")".indexOf(sub) != -1){
                while( "(".indexOf(stack.getLast()) == -1 ){
                    sb.append(stack.removeLast() + " ");
                }
                stack.removeLast();
            }else{
                sb.append(sub + " ");
            }
        }
  
        while(!stack.isEmpty()){ sb.append(stack.removeLast()); }
        return sb.toString();
    }
 
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String str;
  
        while( sc.hasNext() ){
            str = sc.nextLine();
            System.out.println( toPostfix(str) );
        }
    }
}

參考:良葛格學習筆記

Java 大數運算

import java.util.*;
import java.math.*;

public class BigNumberCount{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String str;
  
        while( sc.hasNext() ){
            str = sc.nextLine();
            StringBuffer sb = new StringBuffer(str);
   
            String str1 = sb.substring(0, sb.indexOf(" "));
            sb.delete(0, sb.indexOf(" ")+1);
            String symbol = sb.substring(0, sb.indexOf(" "));
            String str2 = sb.substring(sb.indexOf(" ")+1, sb.length());
            
            BigInteger a = new BigInteger(str1);
            BigInteger b = new BigInteger(str2);
   
            switch( symbol.charAt(0) ){
                case '+':
                    System.out.println( a.add(b) );
                    break;
                case '-':
                    System.out.println( a.subtract(b) );
                    break;
                case '*':
                    System.out.println( a.multiply(b) );
                    break;
                case '/':
                    System.out.println( a.divide(b) );
                    break;
            }  
        }
    }
}

說明

直接使用Java.math底下的BigInteger類別實做

題目

大數運算

參考

超長整數運算（大數運算）

學習筆記

學習筆記:

良葛格學習筆記

Java設計樣式學習心得

學習心得:

如何學習寫程式

程式語言的特性本質（一） 程式語言的特性本質（二）

談程式語言的學習方法

當java程式設計工程師心得 帶新人寫專案心得

Java 迴文

import java.util.Scanner;

public class Palindrome{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                String str;
  
                while( sc.hasNext() ){
                        str = sc.nextLine();
   
                        String tmp = "";
                        int length = str.length() - 1;
                        for(int i = length; i >= 0; i--){
                                tmp += str.charAt(i);
                        }
   
                        if( str.equals(tmp) ){
                                System.out.println("yes");
                        }
                        else{
                                System.out.println("no");
                        }
                }
        }
}

題目
參考程式

Java 阿姆斯壯數

import java.util.Scanner;

public class ArmstrongNumber{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                int a,b;
  
                while( sc.hasNext() ){
                        a = sc.nextInt();
                        b = sc.nextInt();
                        int count = 0;
   
                        for(int i = a; i <= b; i++){
                                boolean ans = false;
                                int length = String.valueOf(i).length();
                                int sum = 0;
                                switch( length ){
                                        case 7:
                                                sum += Math.pow(i/1000000,length);
                                        case 6:
                                                sum += Math.pow((i%1000000)/100000,length);
                                        case 5:
                                                sum += Math.pow((i%100000)/10000,length);
                                        case 4:
                                                sum += Math.pow((i%10000)/1000,length);
                                        case 3:
                                                sum += Math.pow((i%1000)/100,length);
                                        case 2:
                                                sum += Math.pow((i%100)/10,length);
                                        case 1:
                                                sum += Math.pow(i%10,length);
                                                break;
                                }
    
                                if( sum == i ){
                                        System.out.print( i + " ");
                                        count++;
                                }
                        }
   
                        if( count != 0 ){
                                System.out.println();
                        }
                        else{
                                System.out.println("none");
                        }
   
                }
        } 
}

題目

Java 數字翻轉

import java.util.Scanner;

public class NumberTurn{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                String str;
  
                while( sc.hasNext() ){
                        str = sc.nextLine();
   
                        char c [] = str.toCharArray();
                        String tmp = "";
   
                        for( int i = c.length - 1; i >= 0; i-- ){
                                tmp += c[i];
                        }
   
                        System.out.println( Integer.parseInt(tmp) );
                }
        }
}

題目
參考程式

Java 二進位轉換

import java.util.Scanner;

public class CarryTransform{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                int num;
  
                while( sc.hasNext() ){
                        num = sc.nextInt();
   
                        System.out.println( Integer.toBinaryString(num) );
                }
        }
}

題目

Java 最大公因數

import java.util.Scanner;

public class GCD{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                int a,b;
  
                while( sc.hasNext() ){
                        a = sc.nextInt();
                        b = sc.nextInt();
   
                        int i = 0;
   
                        while( b != 0 ){
                                i = a % b;
                                a = b;
                                b = i;
                        }
   
                        System.out.println( a );
                }
        }
}

題目

Java 身分證檢驗

import java.util.Scanner;

public class IdAuthentication{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                String str;
  
                while( sc.hasNext() ){
                        str = sc.nextLine();
                        char c [] = str.toCharArray();
   
                        if( c[0] == 88 || c[0] == 89 ){
                                c[0] -= 58;
                        }
                        else if( c[0] >= 65 && c[0] <= 72 ){
                                c[0] -= 55;
                        }else if( c[0] >= 74 && c[0] <= 78){
                                c[0] -= 56;
                        }else if( c[0] >= 80 && c[0] <= 86){
                                c[0] -= 57;
                        }else{
                                c[0] = (c[0] == 73) ? 34 : (c[0] == 79) ? 35 : 
                                        (c[0] == 87) ? 32 : (c[0] == 90) ? 33 : c[0];
                        }
   
                        int sum = c[0]/10 + (c[0]%10)*9 + (c[9]-48);
   
                        for(int i = 1; i < c.length-1; i++){
                                sum += (c[i]-48)*(9-i);
                        }
   
                        if( sum % 10 == 0 ){
                                System.out.println("real");
                        }
                        else{
                                System.out.println("fake");
                        }
                }
        }
}

題目

Java 數獨判斷

import java.util.Scanner;

public class Sudoku{
    public static int array [][] = new int [9][9];
 
    public static boolean checkRow(int row){
        int sum = 0;
  
        for(int i = 0; i < array.length; i++){
            sum += array[row][i];
        }
  
        if( sum < 45 || sum > 45 ){
            return false;
        }
  
        return true;
    }
 
    public static boolean checkColumn(int column){
        int sum = 0;
  
        for(int i = 0; i < array.length; i++){
            sum += array[i][column];
        }
  
        if( sum < 45 || sum > 45 ){
            return false;
        }
  
        return true;
     }
 
     public static boolean checkLittlePalaceGrid(int box){
         int sum = 0;
         int row = (box / 3) * 3;
         int column = (box < 3) ? box*3 : (box < 6) ? (box - 3)*3 : (box - 6)*3;
  
         for(int i = 0; i < 3; i++){
             for(int j = 0; j < 3; j++){
                 sum += array[i + row][j + column];
             }
         }
  
         if( sum < 45 || sum > 45 ){
             return false;
         }
         return true;
     }

     public static void main(String[] args){
         Scanner sc = new Scanner(System.in);
         boolean row=true,column=true,lpg=true;
  
         while( sc.hasNext() ){
             for(int j = 0; j < 9; j++ ){
                 int a [] = {0,0,0,0,0,0,0,0,0};
                 for(int k = 0; k < 9; k++){
                     a[k] = sc.nextInt();
                 }
                 array[j] = a;
              }
   
              int i = 0;
              while(i < array.length){
                  row = checkRow(i);
                  column = checkColumn(i);
                  lpg = checkLittlePalaceGrid(i);
                  if(row == false || column == false || lpg == false){
                      System.out.println("no");
                      break;
                  }
   
                  if( i == array.length - 1 ){
                      System.out.println("yes");
                  }
                  i++;
              }
         }  
     }
}

題目

Java 矩陣翻轉

import java.util.Scanner;

public class Matrix{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                int row,colum;
                int matrix [][];
  
                while(sc.hasNext()){
                        row = sc.nextInt();
                        colum = sc.nextInt();
                        matrix = new int [row][colum];
   
                        for( int i = 0; i < row; i++ ){
                                for( int j = 0; j < colum; j++){
                                        matrix[i][j] = sc.nextInt();
                                }
                        }

                        for( int i = 0; i < colum; i++ ){
                                for( int j = 0; j < row; j++){
                                        System.out.print(matrix[j][i] + " ");
                                }
                                System.out.println();
                        }
                }
        }
}

題目

Eclipse無法Debug

最近又開始玩android

當要debug的時候竟然出現錯誤

訊息"Error generating final archive: Debug Certificate expired on....."

原因不明，所以就google一下

原來是憑證到期了

解法如下:

第一步: 把"C:\Documents and Settings\user\.android"裡的debug.keystore檔刪除

第二步: 點開時間與日期內容,選時區

第三步: 更新時間，後按確定

第四步: 在eclipse重新建一個專案

第五步: 直接debug讓它重新建置 debug.keystore檔

這樣就OK囉!


參考文章

四位元加法-減法器

專案下載


電路圖:

波形圖:

全加器

專案下載

電路圖:  

波形圖:

Java 羅馬數字

import java.util.*;

public class RomeNumber{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
  
                while(sc.hasNext()){
                        String str [] = sc.nextLine().split(" ");
                        if(str[0].equals("#")){
                                break;
                        }

                        int a = transformIntNumber(str[0]);
                        int b = transformIntNumber(str[1]);
                        int sum = Math.abs(a - b);

                        if( sum == 0){
                                System.out.println("ZERO");
                        }
                        else{
                                System.out.println(transformRomeNumber(sum));
                        }
                }
        } 

        public static int transformIntNumber(String s){
                int count = 0;
                int a [] = new int [s.length()];
                for(int i = 0; i < a.length; i++){
                        switch(s.charAt(i)){
                                case 'I':
                                        a[i] = 1;
                                        break;
                                case 'V':
                                        a[i] = 5;
                                        break;
                                case 'X':
                                        a[i] = 10;
                                        break;
                                case 'L':
                                        a[i] = 50;
                                        break;
                                case 'C':
                                        a[i] = 100;
                                        break;
                                case 'D':
                                        a[i] = 500;
                                        break;
                                case 'M':
                                        a[i] = 1000;
                                        break;
                        }
                }
  
                for(int i = 0; i < a.length; i++){
                        if( i == (a.length - 1)){
                                count += a[i];
                                break;
                        }
                        else if( a[i] < a[i+1] ){
                                count -= a[i];
                        }
                        else{
                                count += a[i];
                        }
                }
  
                return count;
        }

        public static String transformRomeNumber(int a){
                String str = "";
                int index;
                String rome [] = {"I","V","X","L","C","D","M"};
                int num [] = {1,5,10,50,100,500,1000};
                Arrays.sort(num);

                while( a > 0 ){
                        index = Arrays.binarySearch(num, a);
                        if(index == -8){
                                index = 6;
                        }else if(index < 0){
                                index = -1 * index -2;
                                int i = index / 2 * 2;
                                if(a + num[i] >= num[index + 1]){
                                        str += rome[i];
                                        a += num[i];
                                        index++;
                                }
                        }
                        str += rome[index];
                        a -= num[index];
                }
  
                return str;
        }
}

題目
參考程式

驗證圖形驗證碼

index.jsp ----->主頁面

<%@ page language="java" contentType="text/html; charset=BIG5"%>

<form method="post" action="Verification.jsp">
    <img src="dynamicImage"/><br/>
    <input type="text" name="value"></input>
    <input type="submit"></input>
</form>


Verification.jsp ----->驗證

<%@ page language="java" contentType="text/html; charset=big5"%>

<%
    if( request.getParameter("value").equals(session.getAttribute("number")) ){
        out.print("驗證碼正確");
    }else{
        out.print("驗證碼錯誤");
    }
%>


DynamicImage.java ---->產生動態圖形驗證碼

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Iterator;

import javax.imageio.ImageIO;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class DynamicImage extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {
        HttpSession session = request.getSession();
        response.setContentType("image/jpeg");

        BufferedImage bi = new BufferedImage(50,30,BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = bi.createGraphics();
        g2d.setColor(Color.white);
        g2d.fillRect(0, 0, 50, 30);
        g2d.setColor(Color.black);
        g2d.drawRect(5, 5, 40, 20);

        StringBuilder sbl = new StringBuilder();
        while(sbl.length() < 4){
            sbl.append(Integer.toString((int)(Math.random() * 9)));
        }

        session.setAttribute("number", sbl.toString());
  
        g2d.setFont(new Font("Default",Font.BOLD,13));
        g2d.drawString(sbl.toString(), 10, 20);
  
        for(int i = 0; i < 20; i++){
            int x = (int)(Math.random() * 40) + 5;
            int y = (int)(Math.random() * 20) + 5;
   
            g2d.fillOval(x, y, 1, 1);
        }
  
        ServletOutputStream sos = response.getOutputStream();
  
        Iterator ite = ImageIO.getImageWritersByFormatName("jpeg");
        ImageWriter iw = (ImageWriter)ite.next();
  
        ImageOutputStream ios = ImageIO.createImageOutputStream(sos);
        iw.setOutput(ios);
        iw.write(bi);
        ios.flush();
        sos.close();
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>DynamicImage</servlet-name>
    <servlet-class>com.morty.dynamicimage.DynamicImage</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>DynamicImage</servlet-name>
    <url-pattern>/dynamicImage</url-pattern>
  </servlet-mapping>

</web-app>


動態產生密碼圖片

DynamicImage.java

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Iterator;

import javax.imageio.ImageIO;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DynamicImage extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {
        BufferedImage bi = new BufferedImage(50,30,BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = bi.createGraphics();
        g2d.setColor(Color.white);
        g2d.fillRect(0, 0, 50, 30);
        g2d.setColor(Color.black);
        g2d.drawRect(5, 5, 40, 20);
  
        StringBuilder sbl = new StringBuilder();
        while(sbl.length() < 4){
                sbl.append(Integer.toString((int)(Math.random() * 9)));
        }
  
        g2d.setFont(new Font("Default",Font.BOLD,13));
        g2d.drawString(sbl.toString(), 10, 20);
  
        for(int i = 0; i < 20; i++){
                int x = (int)(Math.random() * 40) + 5;
                int y = (int)(Math.random() * 20) + 5;
   
                g2d.fillOval(x, y, 1, 1);
        }
  
        response.setContentType("image/jpeg");
        ServletOutputStream sos = response.getOutputStream();
  
        Iterator ite = ImageIO.getImageWritersByFormatName("jpeg");
        ImageWriter iw = (ImageWriter)ite.next();
  
        ImageOutputStream ios = ImageIO.createImageOutputStream(sos);
        iw.setOutput(ios);
        iw.write(bi);
        ios.flush();
        sos.close();
    }
}

BMI指數

BMI.jsp


<%@ page contentType="text/html; charset=big5"%>

<form method="post" action="BMI.jsp">
    性別:<select name="sex">
        <option></option>
        <option value="man">男</option>
        <option value="woman">女</option>
    </select><br>
    身高(公分):<input type="text" name="height" style="width:5%"/><br>
    體重(公斤):<input type="text" name="weight" style="width:5%"/><br>
    <input type="submit" value="送出">
</form>

<%
    String height = request.getParameter("height");
    String weight = request.getParameter("weight");
    if(height == null || weight == null){
        height = "0.0";
        weight = "0.0";
    }
    String url = "count.jsp?height=" + height + "&weight=" + weight;
%>

<jsp:include page="<%=url%>"></jsp:include>


count.jsp


<%@ page contentType="text/html; charset=big5" %>
<%@
    page import="java.io.*"
%>

<%
    String exponent = "";
    String standard = "";
    int num = 0;
    double h=0.0,w=0.0;

    h = Double.parseDouble(request.getParameter("height")) / 100;
    w = Double.parseDouble(request.getParameter("weight"));

    double ans = w / (Math.pow(h, 2)); //體重 (kg) / 身高 (m)的平方

    if( Double.isNaN(ans) == false){
        exponent = Long.toString(Math.round(ans));
        num = Integer.parseInt(exponent);

        /*
            男性： （身高cm－80）×70﹪＝標準體重
            女性： （身高cm－70）×60﹪＝標準體重
        */
        if(request.getParameter("sex").equals("man")){
            standard = Double.toString(((h*100)-80)*0.7) + " 公斤";
        }else{
            standard = Double.toString(((h*100)-70)*0.6) + " 公斤";
        }
    }

    String str = "";

    //結果
    if( num == 0){
        str = "";
    }else if( num < 18.5 ){
        str = "體重過輕";
    }else if( num > 18.5 && num < 24){
        str = "正常範圍";
    }else if( num >= 24 && num < 27){
        str = "體重過重";
    }else if( num >= 27 && num < 30){
        str = "輕度肥胖";
    }else if( num >= 30 && num < 35 ){
        str = "中度肥胖";
    }else{
        str = "重度肥胖";
    }

%>

<p>BMI 指數:<%=exponent%></p>

<p>結果:<%=str%></p>

<p>標準體重:<%=standard%></p>


web.xml


<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">

    <welcome-file-list>
        <welcome-file>BMI.jsp</welcome-file>
    </welcome-file-list>
</web-app>



Java LCS 最長共同子序列

import java.util.Scanner;

public class LongComSub {
    public static String str1;
    public static String str2;
    public static String result;//記錄共同子序列
 
    public static char [] cha1;
    public static char [] cha2;
 
    public static int [][] array;//LCS表格
    public static String [][] prev;//記錄計算方向
 
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
  
        System.out.print("輸入第一個字串: ");
        str1 = sc.nextLine();
        System.out.print("輸入第二個字串: ");
        str2 = sc.nextLine();
  
        /*str1為短字串  str2為長字串*/
        if(str1.length() > str2.length()){
              String value = str1;
              str1 = "0" + str2;
              str2 = "0" + value;
        }
        else{
              str1 = "0" + str1;
              str2 = "0" + str2;
        }
 
        /*設定陣列長度*/
        array = new int[str1.length()][str2.length()];
        prev = new String[str1.length()][str2.length()];
  
        /*將字串轉換為陣列*/
        cha1 = str1.toCharArray();
        cha2 = str2.toCharArray();
  
        setZero();
  
        countLCS();

        foundValue(cha1.length-1,cha2.length-1);
  
        System.out.print("最長共同子序列: ");
        StringBuffer sb = new StringBuffer(result.substring(4));
        System.out.print(sb.reverse());
    }
 
    /*將 array[x][0] 和 array[0][x] 都設為 0*/
    public static void setZero(){
        for(int i = 0; i < str1.length(); i++){
              array[i][0] = 0;
        } 
        for(int i = 0; i < str2.length(); i++){
              array[0][i] = 0;
        }
    }
 
    /*計算並製作LCS表格*/
    public static void countLCS(){
        System.out.print("  ");
        for(int u = 0; u < cha2.length; u++){
              System.out.print(cha2[u] + " ");
        }
        System.out.println();

        for(int i = 1; i < cha1.length; i++){
              System.out.print(cha1[i] + " ");
              for(int j = 1; j < cha2.length; j++){
                    if( i == 0 || j == 0 ){
                          System.out.print(array[i][j] + " ");
                          continue;
                    }
                    if( cha1[i] == cha2[j] ){
                          array[i][j] = array[i-1][j-1] + 1;
                          prev[i][j] = "左上方";
                          System.out.print(array[i][j] + " ");
                    }
                    else if( array[i-1][j] < array[i][j-1]){
                          array[i][j] = array[i][j-1];
                          prev[i][j] = "左方";
                          System.out.print(array[i][j] + " ");
                    }
                    else{
                          array[i][j] = array[i-1][j];
                          prev[i][j] = "上方";
                          System.out.print(array[i][j] + " ");
                    }
              }
        }
    }
 
    /*找出LCS值*/
    public static void foundValue(int a,int b){
        if(a == 0 && b == 0){
              System.exit(0);
        }
  
        if(prev[a][b] == "左上方"){
              //String初始值null,所以會從null開使加字串
              result += Character.toString(cha1[a]);
              foundValue(a-1,b-1);
        }
        else if(prev[a][b] == "上方"){
              foundValue(a-1,b);
        }
        else if(prev[a][b] == "左方"){
              foundValue(a,b-1);
        }
    }
}

沒有考慮到時間複雜度以及記憶體問題唷

Java 偶基數判斷

一般的比較法

int a = 3;
int b = 4;
 
System.out.println(a%2==0?"a是偶數":"a是奇數");
System.out.println(b%2==0?"b是偶數":"b是奇數");

較快速的比較法

int a = 3;
int b = 4;
 
System.out.println((a&1)==0?"a是偶數":"a是奇數");
System.out.println((b&1)==0?"b是偶數":"b是奇數");

3 & 1 = 0011 & 0001 = 1
4 & 1 = 0100 & 0001 = 0

用%的話就顯得比&還要慢了

來源