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

 public class removeDuplicates {
     public static int[] remove(int[] arr){ 

         int end = arr.length;

         for(int i = 0; i < end; i++){
             for(int j = i + 1; j < end; j++){
                 if(arr[i] == arr[j]){
                     for(int k = j+1; k < end; k++){
                         arr[k-1] = arr[k];
                     }
                     end--;
                     j--;
                 }
             }
         }

         int[] whitelist = new int[end];
         for(int i = 0; i < end; i++){
             whitelist[i] = arr[i];
         }
         System.out.print("new length is ");
         System.out.println(end);
         return whitelist;
     }

     public static void main(String[] args) {
         int[] arr = {3, 2, 1, 3, 2, 1, 3, 2, 1};
         remove(arr);
         for(int i:arr){
             System.out.print(i);
             System.out.print(", ");
         }
     }
 }

Selection Sort Ascending order, 它的错误在于7行大于小于错误

     public static int[] doSelectionSort(int[] arr){

         for (int i = 0; i < arr.length-1; i++)
         {
             int index = i;
             for (int j = i + 1; j < arr.length; j++)
                 if (arr[j] < arr[index])
                     index = j;

             int smallerNumber = arr[index];
             arr[index] = arr[i];
             arr[i] = smallerNumber;
         }
         return arr;
     }

Selection Sort Dscending order, 他的错误在于第5行大于小于错误

     public static int[] doSelectionSort(int[] arr){
         for (int i=0; i<arr.length-1; i++) {
             int max = i;
             for (int j=1; j<arr.length; j++) {
                 if (max < arr[j]) {
                     max = j;
                 }
             }
             if (max != i) {
                 int temp = arr[i];
                 arr[i] = arr[max];
                 arr[max] = temp;
             }
         }
         return arr;
     }

Reverse an int array, 它的问题在于第3行忘了-1

 for (int i=0; i<arr.length/2; i++) {
    int temp = arr[i];
    arr[i] = arr[arr.length-1-i];
    arr[arr.length-1-i] = temp;  

 }

Print Pattern, 打印11， 1111, 111111，中间需要换行，它的问题在于括号少打了