Remove Duplicates from unsorted array,它的错误在于9-10行k out of bound，改成下面这样就没问题了
1 public class removeDuplicates { 2 public static int[] remove(int[] arr){ 3 4 int end = arr.length; 5 6 for(int i = 0; i < end; i++){ 7 for(int j = i + 1; j < end; j++){ 8 if(arr[i] == arr[j]){ 9 for(int k = j+1; k < end; k++){ 10 arr[k-1] = arr[k]; 11 } 12 end--; 13 j--; 14 } 15 } 16 } 17 18 int[] whitelist = new int[end]; 19 for(int i = 0; i < end; i++){ 20 whitelist[i] = arr[i]; 21 } 22 System.out.print("new length is "); 23 System.out.println(end); 24 return whitelist; 25 } 26 27 public static void main(String[] args) { 28 int[] arr = {3, 2, 1, 3, 2, 1, 3, 2, 1}; 29 remove(arr); 30 for(int i:arr){ 31 System.out.print(i); 32 System.out.print(", "); 33 } 34 } 35 }
Selection Sort Ascending order, 它的错误在于7行大于小于错误
1 public static int[] doSelectionSort(int[] arr){ 2 3 for (int i = 0; i < arr.length-1; i++) 4 { 5 int index = i; 6 for (int j = i + 1; j < arr.length; j++) 7 if (arr[j] < arr[index]) 8 index = j; 9 10 int smallerNumber = arr[index]; 11 arr[index] = arr[i]; 12 arr[i] = smallerNumber; 13 } 14 return arr; 15 }
Selection Sort Dscending order, 他的错误在于第5行大于小于错误
1 public static int[] doSelectionSort(int[] arr){ 2 for (int i=0; i<arr.length-1; i++) { 3 int max = i; 4 for (int j=1; j<arr.length; j++) { 5 if (max < arr[j]) { 6 max = j; 7 } 8 } 9 if (max != i) { 10 int temp = arr[i]; 11 arr[i] = arr[max]; 12 arr[max] = temp; 13 } 14 } 15 return arr; 16 }
Reverse an int array, 它的问题在于第3行忘了-1
1 for (int i=0; i<arr.length/2; i++) { 2 int temp = arr[i]; 3 arr[i] = arr[arr.length-1-i]; 4 arr[arr.length-1-i] = temp; 5 6 }
Print Pattern, 打印11， 1111, 111111，中间需要换行，它的问题在于括号少打了