‪#‎Javafest_Brain_Tweaker‬ # 1 from https://www.facebook.com/therapjavafest/posts/591777984278321

problem statement

Find an Array
Implement a method that given two arrays as parameters will find the starting index where the second parameter occurs as a sub-array in the array given as the first parameter.
Your implementations should return -1 if the sub-array cannot be found.
Your implementation must implement the FindArray interface given bellow:
public interface FindArray {
int findArray(int[] array, int[] subArray);
}
Sample Input:
[4,9,3,7,8] and [3,7] should return 2.
[1,3,5] and [1] should return 0.
[7,8,9] and [8,9,10] should return -1.
Sample Code :
public class MyFindArray implements FindArray {
public int findArray(int[] array, int[] subArray) {
return -1;
}
}

src_FindArray.java

public interface FindArray {
int findArray(int[] array, int[] subArray);
}

src_SubArray.java

import java.util.Arrays;

/**
 * Created by ahmed on 10/16/2014.
 */
public class SubArray implements FindArray {
    @Override
    public int findArray(int[] array, int[] subArray) {
        int firstArrayLength = array.length;
        int secondArrayLength = subArray.length;
        if (firstArrayLength == secondArrayLength) {
            return Arrays.equals(array, subArray) ? 0 : -1;
        } else if (firstArrayLength > secondArrayLength) {
            boolean flag = false;
            for (int i = 0, j = firstArrayLength; j >= secondArrayLength; i++, j--) {
                if (hasSubArray(array, subArray, i, i + secondArrayLength)) {
                    flag = true;
                    return i;
                }
            }
            if (!flag) return -1;
        } else {
            return -1;
        }
        return 0;
    }

    private boolean hasSubArray(int[] array, int[] subArray,
                                int from, int to) {
        int[] tempArray = Arrays.copyOfRange(array, from, to);
        return Arrays.equals(tempArray, subArray);
    }

    // for test purpose 
    public static void main(String[] args) {
        SubArray subArray = new SubArray();
        int[] array = {1,3,5};
        int[] sub_array = {1};
        System.out.println(subArray.findArray(array, sub_array));
    }
}