/**
* Concat arrays in one.
*
* @param arrays Arrays.
* @return Summary array.
*/
public static int[] concat(int[]... arrays) {
assert arrays != null;
assert arrays.length > 1;
int len = 0;
for (int[] a : arrays) len += a.length;
int[] r = Arrays.copyOf(arrays[0], len);
for (int i = 1, shift = 0; i < arrays.length; i++) {
shift += arrays[i - 1].length;
System.arraycopy(arrays[i], 0, r, shift, arrays[i].length);
}
return r;
}
