/** *//**父子倆的年齡：父親今年30歲，兒子今年6歲，問多少年後父親的年齡是兒子年齡的2倍。*/
package exec;public class Age ...{
public static void main(String[] args) ...{ // TODO Auto-generated method stub int father = 30; int son = 6; for(int i=1;i<100;i++) ...{ if((father+i)==((son+i)*2))...{ System.out.println(i + " 年");
} } }
}
/** *//**編寫程序,將兩個各有6個整數的數組,合併成一個由小到大排列的數組,(該數組的長度爲12)*/package exec;import java.util.Arrays;public class Arrary ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub int a[] = ...{ 1, 3, 5, 8, 9, 4 }; int b[] = ...{ 2, 4, 7, 6, 5, 9 }; int c[] = new int[12]; for (int i = 0; i < 6; i++) ...{ c[i] = a[i]; c[i + 6] = b[i]; } Arrays.sort(c); for (int i = 0; i < 12; i++) ...{ System.out.print(c[i] + " "); } }}
/** *//** 一個球從100米高度自由落下後，反彈回原來高度的一半。按此規律，到第10次落地時，行程共有多少米？ * 然後將反彈起多高？ */package exec;public class BallFall ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub float heigher = 100; float sum = 0; for (int i = 1; i < 10; i++) ...{ heigher /= 2; sum += heigher; System.out.println("第" + i + "次" + "總行程" + sum + "米" + "反彈" + heigher + "米"); } }}
/** *//** 換硬幣：把一元人民幣換成5分、2分、1分的硬幣，有多少種換法? */package exec;public class ChangeCoin ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub int num = 0; for (int i = 1; i <= 20; i++) ...{ for (int j = 1; j <= 50; j++) ...{ for (int k = 1; k <= 100; k++) ...{ if (5 * i + 2 * j + 1 * k == 100) ...{ num += 1; } } } } System.out.print(num + "種換法"); }}
/** *//**牛的繁殖問題 ：有位科學家曾出了這樣一道數學題：有一頭母牛，它每年年初要生一頭小母牛； * 每頭小母牛從第四個年頭起，每年年初也要生一頭小母牛。按此規律，若無牛死亡，第20年頭上共有多少頭母牛？*/package exec;public class CountCow ...{ int[] cowNumber = new int[21]; public void count(int increaseCycle, int years) ...{ cowNumber[0] = 1; for (int currentYear = 1; currentYear <= years; currentYear++) ...{ if (currentYear < increaseCycle) ...{ cowNumber[currentYear] = cowNumber[currentYear - 1] + 1; } else ...{ cowNumber[currentYear] = cowNumber[currentYear - 1] + cowNumber[currentYear - increaseCycle + 1]; } System.out .println("第" + currentYear + "年" + cowNumber[currentYear]); } } public static void main(String[] args) ...{ int increaseCycle = 4; int years = 20; CountCow cow = new CountCow(); cow.count(increaseCycle, years); }}
/** *//** 打印出500之內所有能被7或9整除的數*/package exec;public class Divide ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub for (int i = 0; i <= 500; i++) ...{ if ((i % 7 == 0) | (i % 9 == 0)) ...{ System.out.print(i + " "); } } }}
/** *//** * 編寫一個Java程序 使它隨即產生1800到2000之間的年份,打印它是否是一個閏年,閏年是1584年以後的年份,它要能被400整除, * 要能被4整除但是不能被100整除,已知使用Math.random()方法可以產生0到1之間的隨即小數. ) */package exec;public class EmergerYear ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub for (int i = 0; i < 100; i++) ...{ long year = (Math.round(Math.random() * 200) + 1800); if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) ...{ System.out.println(year + "是閏年!"); } else System.out.println(year + "不是閏年!"); } }}
/** *//**編寫程序以遞歸的方式實現1+2+3+...+n(n=200)的計算.*/package exec;public class Number ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub System.out.print(numbers(200)); } public static int numbers(int n)...{ return n<=1?1:n+numbers(n-1); }}
/** *//** 給定一個數，並由鍵盤輸入若干個數，找出與預先給定的數最接近的數， * 並指出它是由鍵盤輸入的第幾個數。 */package exec;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;public class NumberCompare ...{ public static final int NUMBER = 80; // 給定一個要比較的數 public static void main(String args[]) ...{ System.out.print("Please input numbers: "); BufferedReader io = new BufferedReader(new InputStreamReader(System.in)); try ...{ // 從鍵盤輸入若干數 String line = io.readLine(); // 放入數組中 String[] items = line.split(" "); int temp = 5000, x = 0, place = 0; System.out.println("target number: 80"); // 和給定的數比較大小 for (int i = 0; i < items.length; i++) ...{ if (Integer.parseInt(items[i]) > NUMBER) ...{ x = Integer.parseInt(items[i]) - NUMBER; } else ...{ x = NUMBER - Integer.parseInt(items[i]); } if (x < temp) ...{ temp = x; place = Integer.parseInt(items[i]); } } System.out.println("place: " + place); io.close(); System.exit(0); } catch (IOException e) ...{ e.printStackTrace(); } }}
/** *//**使用Java,long.Math類,生成10個0到99之間的隨即整數,求出它們中的最小值和最大值*/package exec;import java.util.Iterator;import java.util.TreeSet;public class RandomNumber ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub /** *//**方法1 long max = 50; long min = 50; for(int i=0; i<10; i++){ long number = Math.round(Math.random()*99 + 1); System.out.print(number + " "); max = Math.max(max, number); min = Math.min(min, number); if(i == 9){ System.out.print(" Math MaxNumber=" + max + " MinNumber=" + min); } } */ //方法2 TreeSet ts = new TreeSet(); for(int i=0; i<10; i++)...{ long number = Math.round(Math.random()*99 + 1); System.out.print(number + " "); ts.add(number); } System.out.println(); Iterator it = ts.iterator(); while(it.hasNext())...{ System.out.print(it.next() + " "); } System.out.print(" Math MaxNumber=" + ts.last() + " MinNumber=" + ts.first()); } }
/** *//**假設有一條鋼材長2000米,每天截取其中的一半,編寫一程序求出多少天后,鋼材的長度小於5米.*/package exec;public class SteelSection ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub int i = 0; float steel = 2000f; while (steel >= 5) ...{ i++; steel = steel / 2; System.out.println(i + "天后鋼管長" + steel + "米"); } }}
/** *//**完全數是指其所有因子(包括1但不包括該數自身)的和等於該數,例如28=1+2++4+7+14,28就是一個完全數. * 編寫一個程序求出2到10000之間的所有完全數.*/package exec;public class WanNumber ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub int m = 0; for (int n = 2; n <= 10000; n++) ...{ m = 0; for (int i = 1; i < n; i++) ...{ if (n % i == 0) ...{ m += i; if (m == n) ...{ System.out.println(n + "個完全數"); } } } } }}
/**//*編寫一個Java類Prime,其中只有一個靜態方法. boolean.isPrin=me(int n)//方法測試n是否是素數, * 如果是返回true 否則返回false 已知Babbage函數發f（x)=x*x+x+41,其中x爲自然數, * 當x小於特定的n之間所有的函數均爲素數,編寫一個測試類,其中的main方法找出這個特定n值. */package exec;public class Test ...{ public static void main(String[] args) ...{ // TODO Auto-generated method stub int num = 200000; // 表示1-num之間的自然數 for (int i = 1; i <= num; i++) ...{ if (Prime.me(i)) ...{ System.out.println(i + "是素數"); } else ...{ System.out.println(i + "不是素數"); } } }}package exec;public class Prime ...{ public static boolean me(int n) ...{ for (int x = 1; x < n; x++) ...{ if (n == x * x + x + 41) ...{ return true; } } return false; }}