1.数列(1,1,2,3,5,8,13...)第i位是多少?
1 /// <summary> 2 /// 递归 3 /// </summary> 4 public int Foo(int i) 5 { 6 if (i <= 0) 7 return 0; 8 else if (i > 0 && i <= 2) 9 return 1; 10 else 11 return Foo(i - 1) + Foo(i - 2); 12 }
2.求数列(1,1,2,3,5,8,13...)的和。
1 public int Sum(int index) 2 { 3 int sum = 0; 4 for (int i = 1; i <= index; i++) 5 sum += Foo(i); 6 return sum; 7 }
3.求1-2+3-4+5-6...+m的值
1 public int Sum(int m) 2 { 3 int sum = 0; 4 if (m <= 0) return 0; 5 for (int i = 1; i <= m; i++) 6 { 7 if (i % 2 == 0) 8 sum -= i; 9 else 10 sum += i; 11 } 12 return sum; 13 }
4.写一个简单的冒泡排序
1 /// <summary> 2 /// 冒泡排序 3 /// </summary> 4 public Array BubbleSort(int[] array) 5 { 6 if (array == null || array.Length <= 0) 7 return null; 8 int temp = 0; 9 10 for (int i = 0; i < array.Length - 1; i++) 11 { 12 for (int j = 0; j < array.Length - 1 - i; j++) 13 { 14 if (array[j] > array[j + 1]) 15 { 16 temp = array[j]; 17 array[j] = array[j + 1]; 18 array[j + 1] = temp; 19 } 20 } 21 } 22 23 return array; 24 }