Amazon OA

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