1、求2+22+222+2222+22222的和?

1 package com.KiloPhone.Fouthday; 2  3 import java.util.Scanner; 4  5 /** 6  * 求2+22+222+2222+22222的和? 7  */ 8 public class TestAlgorithm { 9     public static void main(String[] args) {10         Scanner scann = new Scanner(System.in);11         // 基数12         int i = scann.nextInt();13         // 次数14         int j = scann.nextInt();15         // 中间变量16         int k = 0;17         // 和18         int sum = 0;19         20         for(int m = 1; m <= j; m++){21             k = k * 10 + i;22             sum += k;23         }24         System.out.println(sum);25     }26 }

2、Fibonacci数列：1 1 2 3 5 8 13...

 （1）第一种方法：

1 class Fibonacci { 2     public static void main(String[] args) { 3         int a = 1; 4         int b = 1; 5         int c = 0; 6  7         for (int i = 3; i <= 12; i++) { 8             c = a + b; 9             a = b;10             b = c;11         }12         System.out.println(c);13     }14 }

（2）第二种方法（递归）：

1 package com.kiloPhone.sixthClass; 2  3 import java.util.Scanner; 4  5 /** 6  * Fibonacci数列 7  */ 8 public class TestFibonacci { 9 10     public static int getfibonacci(int n) {11         if (n == 1 || n == 2) {12             return 1;13         }14         return getfibonacci(n - 1) + getfibonacci(n - 2);15     }16 17     /**18      * @param args19      */20     public static void main(String[] args) {21         // TODO Auto-generated method stub22         Scanner scann = new Scanner(System.in);23         System.out.println(getfibonacci(scann.nextInt()));24     }25 26 }

3、冒泡排序法

1 // 冒泡排序法 2 class BubbleSort  3 { 4     public static void bubbleSort(int[] intArr){ 5         int temp; 6         for (int i = intArr.length - 1; i > 0;i-- ) 7         { 8             boolean isSort = false; 9             for (int j = 0; j < i; j++)10             {11                 if (intArr[j + 1] < intArr[j] )12                 {13                     temp = intArr[j];14                     intArr[j] = intArr[j + 1];15                     intArr[j + 1] = temp;16                     isSort = true;17                 }18             }19             if (!isSort)20             {21                 break;22             }23         }24     }25     public static void main(String[] args) 26     {27         int[] intArray = {1,25,12,7,89,56,23,25};28         System.out.println("排序前的值：");29         for(int i : intArray)30         {31             System.out.println(i);32         }33         bubbleSort(intArray);34         System.out.println("排序后的值：");35         for(int i : intArray)36         {37             System.out.println(i);38         }39     }40 }