## Monday, January 25, 2016

### Amazon OA

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
``` 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     }
```
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 }```

Amazon OA