/// <summary>
/// Select the Stack that has the maximum element of the two stack for processing
/// and use the other stack to keep elements yet to be processed.
/// </summary>
/// <param name="stack1"></param>
/// <param name="stack2"></param>
private static void SelectStackForProcessing(ref StackMax stack1, ref StackMax stack2)
{
StackMax temp = null;
if (!stack1.isEmpty() && !stack2.isEmpty())
{
Item item1 = stack1.peek();
Item item2 = stack2.peek();
// In case Stack 2 has the largest element then swap stack1 and stack2
if (item1.Max < item2.Max)
{
temp = stack1;
stack1 = stack2;
stack2 = temp;
}
}
else if (stack1.isEmpty() && !stack2.isEmpty())
{
temp = stack1;
stack1 = stack2;
stack2 = temp;
}
}
public static void ShuffleElements(int[] input)
{
int n = input.Length;
StackMax stack1 = new StackMax(n);
StackMax stack2 = new StackMax(n);
for (int i = 0; i < n; i++)
{
Item newItem = new Item(input[i]);
stack1.push(newItem);
}
int prevMax = int.MinValue;
int start = 0;
int end = n - 1;
bool isFront = true;
// Indicator to see how many times we are going to the loop.
int operations = 0;
// Stack1 is used to extract the Maximum element and stack2 is used to maintain the elements placed in it's proper position.
while (!stack1.isEmpty() || !stack2.isEmpty())
{
operations++;
SelectStackForProcessing(ref stack1, ref stack2);
Item item = stack1.pop();
int max = item.Max;
// If the element value is not the same as the Max value, then it means the current element
// is not the one that is placed in correct position. but it is the maximum in the stack that is placed in it's correct
// position. Push the current element to stack2 for later processing.
if (item.Data != max)
{
item.Max = item.Data;
stack2.push(item);
}
// If PrevMax is not same as current max that means a new maximum has been identified.
if (prevMax != max)
{
// IsFront is used to flip the order of insertion of elements.
if (isFront)
{
input[start] = max;
start++;
}
else
{
input[end] = max;
end--;
}
isFront = !isFront;
prevMax = max;
}
}
Console.WriteLine();
Console.WriteLine("Number of Operations " + operations.ToString());
}