public static int LasVegasRandomizedSelect(int[] array, string arrayName, int start, int end, int i, AlgorithmsAnimation animation)
{
animation.PushFunctionStack("Select");
animation.DeclareVariable("start");
animation.DeclareVariable("end");
animation.DeclareVariable("i");
animation.SetVariable("start", start.ToString());
animation.SetVariable("end", end.ToString());
animation.SetVariable("i", i.ToString());
if (start == end)
{
animation.PopFunctionStack();
return(array[start]);
}
int pivot = Partition(array, arrayName, start, end, rand.Next(start, end + 1), animation);
animation.DeclareVariable("pivot");
animation.SetVariable("pivot", pivot.ToString());
int k = pivot - start + 1;
animation.DeclareVariable("k");
animation.SetVariable("k", k.ToString());
int res;
if (k == i)
{
res = array[pivot];
}
else if (i < k)
{
res = LasVegasRandomizedSelect(array, arrayName, start, pivot - 1, i, animation);
}
else
{
res = LasVegasRandomizedSelect(array, arrayName, pivot + 1, end, i - k, animation);
}
animation.PopFunctionStack();
return(res);
}
public static int Partition(int[] array, string arrayName, int start, int end, int pivotId, AlgorithmsAnimation animation)
{
animation.PushFunctionStack($"Partition");
animation.DeclareVariable("start");
animation.DeclareVariable("end");
animation.DeclareVariable("pivotId");
animation.SetVariable("start", start.ToString());
animation.SetVariable("end", end.ToString());
animation.SetVariable("pivotId", pivotId.ToString());
int x = array[pivotId];
animation.DeclareVariable("pivot");
animation.SetVariable("pivot", x.ToString());
Swap(array, arrayName, pivotId, end, animation);
int i = start;
animation.DeclareVariable("i");
animation.SetVariable("i", i.ToString());
animation.DeclareVariable("j");
for (int j = start; j <= end; j++)
{
animation.SetVariable("j", j.ToString());
if (array[j] < x)
{
Swap(array, arrayName, i++, j, animation);
animation.SetVariable("i", i.ToString());
}
}
Swap(array, arrayName, i, end, animation);
animation.PopFunctionStack();
return(i);
}