private static IntPair[] getRandomizedIntPairs(int num, Random rnd) {
IntPair[] pairs = new IntPair[num];
// create all the pairs, dense
for (int i = 0; i < num; i++) {
pairs[i] = new IntPair(i, i + KEY_VALUE_DIFF);
}
// randomly swap them
for (int i = 0; i < 2 * num; i++) {
int pos1 = rnd.nextInt(num);
int pos2 = rnd.nextInt(num);
IntPair tmp = pairs[pos1];
pairs[pos1] = pairs[pos2];
pairs[pos2] = tmp;
}
return pairs;