2014.10.17--Java基础课第四天学习总结

1.五人分鱼问题

package com.day1017;/** * 五人分鱼问题 * 每次分成5份多1条，分五次，求至少多少条鱼。 * @author hechao * */public class Test01 {public static void main(String[] args) {// 穷举法for (int i = 1;; i++) {int fish = i;// 用变量fish记录下假设的鱼的条数boolean isEnough = true;// 鱼还够不够分for (int j = 1; isEnough && j <= 5; j++) {if ((fish - 1) % 5 == 0) {fish = (fish - 1) * 4 / 5;} else {isEnough = false;// 鱼不够分了}}if (isEnough) {System.out.println(i);break;}}}}</span>

2.打印1-100之间的素数

package com.day1017;/** * 打印1-100之间的素数 * 只能被1和自身整除的数 * 判断2到n-1之间是否有因子 *  * @author 何超 * */public class Test02 {public static void main(String[] args) {System.out.println("1到100的素数有："); for(int i = 1; i <= 100; i++){ boolean isPrime = true;//用布尔值表示i是不是素数for(int j = 2; isPrime && j <= i - 1; j++){//for(int j = 2; isPrime && j <= Math.sqrt(i); j++){//在2到根号i之间寻找i的因子if (i % j == 0){isPrime = false;//不是素数讲布尔值赋为false}}if(isPrime) {System.out.print(i + ", ");}}}}

3.将素数和阶乘方法保存为常用方法，方便调用

package com.day1017;/** * 将该方法保持为方法，方便调用 * 打印1-100之间的素数 * 只能被1和自身整除的数 * 判断2到n-1之间是否有因子 *  * @author 何超 * */public class Test03 {public static boolean isPrime(int n) {//素数判定for(int j = 2; j <= Math.sqrt(n); j++){if (n % j == 0) {return false;}}return true;}//将判断是否为素数存储为一个isPrime方法，方便以后调用 public static double jc(int n){//阶乘//进入数 double result = 1; // 累乘变量for (int i = 1; i <= n; i++) {result *= i;}return(result);//返回数}//阶乘public static void main(String[] args) {double n = 0;for(int i = 1; i <= 9; i++){n += jc(i);}System.out.printf("%.0f",n);}}

4.计算两个数的最大公约数 

package com.day1017;import java.util.Scanner;/** * 计算最大公约数（greateest common divisor） *  * @param x * @param y * @return返回 参数x和y的最大公约数 * @author hechao * */public class Test04 {public static  int gcd(int x,int y){for(int i = x < y ? x : y; i > 1; i--){if(x % i == 0 && y % i == 0){return i;}}return 1;}public static void main(String[] args) {Scanner sc = new Scanner(System.in);System.out.println("请输入第一个数：");int a = sc.nextInt();System.out.println("请输入的二个数：");int b = sc.nextInt();int c = gcd(a,b);System.out.printf("%d和%d的最大公约数是:%d",a,b,c);sc.close();}}

5.七星彩随机选号程序

package com.day1017;import java.util.Scanner;/** * 七星彩随机选号程序 * 输入购买彩票注数n，输出n注7个0到9的随机数 * @author hechao * */public class Test05 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);System.out.print("请输入所购七星彩注数：");int n = sc.nextInt();for(int a = 1; a <= n; a++){for(int i = 1; i <= 7; i++){int j = (int)(Math.random() * 10);System.out.print(j+" ");}System.out.println();}sc.close();}}

6.猜数字游戏

package com.day1017;import java.util.Scanner;/** * 猜数字游戏 *  * @author hechao * */public class Test06 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int counter = 0;int answer = (int) (Math.random() * 100 + 1);int yourAnswer;do {counter++;System.out.println("亲，你猜的数字是：");yourAnswer = sc.nextInt();if (answer > yourAnswer) {System.out.println("亲，再大一点！");} else if (answer < yourAnswer) {System.out.println("亲，再小一点！");} else {System.out.println("恭喜你，猜对了！");System.out.println("亲，你猜了" + counter + "次");}} while (yourAnswer != answer);sc.close();}}

7.Craps赌博游戏 

package com.day1017;/** * Craps赌博游戏  * @author hechao * */public class Test07 { /** * 摇一颗骰子 * @return 摇出点数 */ public static int roll(){return (int) (Math.random() * 6 + 1); }public static void main(String[] args) {int firstPoint, currentPoint;firstPoint = currentPoint = roll() + roll();System.out.println("玩家摇出了" + currentPoint + "点");boolean goon = false;switch(currentPoint){case 7:case 11:System.out.println("玩家胜！！！");break;case 2:case 3:case 12:System.out.println("庄家胜！！！");break;default:goon = true; }while(goon) {currentPoint = roll() + roll();System.out.println("玩家摇出了" + currentPoint + "点");if(currentPoint == 7) {System.out.println("庄家胜！！！");goon = false;}else if(currentPoint == firstPoint) {System.out.println("玩家胜！！！");goon = false;}}}}

8.求10000以内的完美数

package com.day1017;/** * 求10000以内的完美数 * 完美数（等于自己因子和的数） * 6=1+2+3 * 28=1+2+4+7+14 * @author hechao * */public class Test08 {public static void main(String[] args) {System.out.print("10000以内的完美数有：");for(int num = 1; num <= 10000; num++){int sum = 0;for(int facter = 1; facter <= num / 2; facter++){if(num % facter == 0){ sum += facter;}else{continue;}}if(sum == num){System.out.print(num + " ");}}}}

9.21根火柴游戏

package com.day1017;import java.util.Scanner;/** * 21根火柴游戏 * 人先抽，每次只能抽1到4根，谁最后抽谁输。 * @author hechao * */public class Test09 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);//int counter = 0;int sum = 21;int sum1 = 21;for (; sum1 > 0 && sum > 0; ) {System.out.print("请输入你抽取的火柴数：");int myNum = sc.nextInt();sum1 = 21;sum1 -= myNum;int computerNum = 5 - myNum;System.out.printf("计算机抽取了%d根火柴\n", computerNum);sum -= 5;if(sum1 == 1){System.out.println("玩家胜！！！");break;}if(sum == 1){System.out.println("电脑胜！！！");break;}}sc.close();}}

10.谁是小偷

package com.day1017;/** * 谁是小偷 * a说：b没偷，d偷的； * b说：我没偷，c偷得； * c说：a没偷，b偷的； * d说：我没偷。谁是小偷？ * @author hechao *  */public class Test10 {public static void main(String[] args) {int a, b, c, d;for(int i = 0; i <= 1; i++){for(int j = 0; j <= 1; j++){if(i == 0){//i==0表示a说谎，对应的d说的是事实。b = 1; d = 0;//偷用1表示，没偷用0表； }else{//a说的是事实，则d说谎。b = 0; d = 1;}if(j == 0){//j==0表示b说谎，对应的c说的是事实。a = 0; b = 1; c = 0; }else{//b说的是事实，则c说谎；a = 1; b = 0; c = 1;}if(a==1&&b==0&&c==0&&d==0){System.out.println("a是小偷！！！");break;}if(b==1&&a==0&&c==0&&d==0){System.out.println("b是小偷！！！");break;}if(c==1&&b==0&&a==0&&d==0){System.out.println("c是小偷！！！");break;}if(d==1&&b==0&&c==0&&a==0){System.out.println("d是小偷！！！");break;}}}}}