public HashTable(int ll, HashFuncType hashfunction)
{
func = hashfunction;
l = ll;
var uni = Math.Pow(2, l);
// here we create an empty list of lists
hashT = new List <List <MutableKeyValuePair <int, int> > >();
for (int i = 0; i < uni; i++)
{
hashT.Add(new List <MutableKeyValuePair <int, int> >());
}
}
static UInt64 SFunc(IEnumerable <Tuple <ulong, int> > stream, int l, HashFuncType funcType)
{
// we begin by storing the key value pairs in the hash table using the hashfunctions
HashTable hashTable = new HashTable(l, funcType);
// the loop below computes s(x)
var watch = new Stopwatch();
watch.Start();
foreach (Tuple <ulong, int> pair in stream)
{
if (hashTable.get(pair.Item1) == 0) // key does not exist
{
hashTable.set(pair.Item1, pair.Item2); // put key value pair in hashtable
}
else // key exists
{
hashTable.increment(pair.Item1, pair.Item2); // add value to already existing key value
}
}
watch.Stop();
Console.WriteLine("Hashing to table took " + watch.ElapsedMilliseconds + "ms.");
watch.Reset();
watch.Start();
// next we add the s(x)^2 above to compute S, as required
UInt64 sum = 0UL;
foreach (List <MutableKeyValuePair <int, int> > lst in hashTable.hashT)
{
foreach (MutableKeyValuePair <int, int> pair in lst)
{
sum += (ulong)Math.Pow(pair.Value, 2);
}
}
watch.Stop();
Console.WriteLine("Calculating S took " + watch.ElapsedMilliseconds + "ms.");
Console.WriteLine("S is:" + sum);
return(sum);
}
static void Exercise3(HashFuncType type)
{
Console.WriteLine("type: " + type + "\nn=1,000,000" + "\n___________");
// l=1 .. 25
// n=1000000
int n = 1000000;
List <int> llist = new List <int> {
5, 10, 15, 20, 25
};
var watch = new Stopwatch();
foreach (int lval in llist)
{
Console.WriteLine("l-value: " + lval);
watch.Start();
SFunc(Generator.CreateStream(n, lval), lval, type);
watch.Stop();
Console.WriteLine("total time: " + watch.ElapsedMilliseconds);
Console.WriteLine();
watch.Reset();
}
}
