/// <summary>
/// Find duplicates in an array with only 4kb of memory available
/// </summary>
/// <param name="arr"></param>
public static void FindDuplicates(int[] arr)
{
BitVector bv = new BitVector(32000);
for (int i = 0; i < arr.Length; i++)
{
int num = arr[i];
int num0 = num - 1;
if (bv.Get(num0))
{
Console.WriteLine("Duplicate: " + num);
}
else
{
bv.Add(num0);
}
}
}
public void BitVectorTests_Basics()
{
BitVector vector = new BitVector(false, 260);
HashSet <int> expected = new HashSet <int>();
// Empty vector
vector.Trim();
VerifySame(expected, vector);
Assert.Null(vector.Array);
Assert.Equal(260, vector.Capacity);
// Add every third item
for (int i = 0; i < vector.Capacity; i += 3)
{
// True the first time
Assert.Equal(expected.Add(i), vector.Add(i));
// False when already present
Assert.Equal(expected.Add(i), vector.Add(i));
}
VerifySame(expected, vector);
// Remove every sixth item
for (int i = 0; i < vector.Capacity; i += 6)
{
// True the first time
Assert.Equal(expected.Remove(i), vector.Remove(i));
// False when already present
Assert.Equal(expected.Remove(i), vector.Remove(i));
}
VerifySame(expected, vector);
// Contains
for (int i = 0; i < vector.Capacity; ++i)
{
Assert.Equal(expected.Contains(i), vector.Contains(i));
}
// Verify untyped enumerator, Reset()
List <int> expectedList = new List <int>(expected);
IEnumerator untyped = ((IEnumerable)vector).GetEnumerator();
int index = 0;
while (untyped.MoveNext())
{
Assert.Equal(expectedList[index], untyped.Current);
index++;
}
untyped.Reset();
index = 0;
while (untyped.MoveNext())
{
Assert.Equal(expectedList[index], untyped.Current);
index++;
}
// Automatic growth w/default (need 126 ints = 4,001 / 32 rounded up)
vector.Add(4000);
expected.Add(4000);
Assert.Equal(4001, vector.Capacity);
Assert.Equal(((4001 + 31) / 32), vector.Array?.Length ?? 0);
VerifySame(expected, vector);
// Clear
vector.Clear();
Assert.Empty(vector);
Assert.Equal(0, vector.Capacity);
// UnionWith
vector.UnionWith(expected);
VerifySame(expected, vector);
// ExceptWith
vector.ExceptWith(expected);
Assert.Empty(vector);
// SetAll
vector.Clear();
vector[100] = true;
vector.SetAll(true);
Assert.Equal(vector.Capacity, vector.Count);
Assert.False(vector[vector.Capacity]);
Assert.True(vector[vector.Capacity - 1]);
vector.SetAll(false);
Assert.Empty(vector);
Assert.False(vector[vector.Capacity]);
// SetAll (exact multiple of 32)
vector.Clear();
vector[3999] = true;
vector.SetAll(true);
Assert.Equal(vector.Capacity, vector.Count);
Assert.False(vector[vector.Capacity]);
Assert.True(vector[vector.Capacity - 1]);
vector.SetAll(false);
Assert.Empty(vector);
Assert.False(vector[vector.Capacity]);
Assert.False(vector[vector.Capacity - 1]);
}
