static string RearrangeStringKApart(string str, int k)
{
// populate dictionary
// populate max heap
// get the top element
// add to the result , decrement the counter
// add the element to
Queue <Element> queue = new Queue <Element>();
Dictionary <char, int> dict = new Dictionary <char, int>();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < str.Length; i++)
{
if (!dict.ContainsKey(str[i]))
{
dict.Add(str[i], 0);
}
dict[str[i]]++;
}
MaxHeap maxHeap = new MaxHeap(dict.Count);
foreach (var entry in dict)
{
maxHeap.Insert(new Element(entry.Key, entry.Value));
}
while (maxHeap.Count > 0)
{
Element current = maxHeap.Delete();
sb.Append(current.Character);
current.Frequency--;
if (current.Frequency > 0)
{
queue.Enqueue(current);
}
if (queue.Count == k)
{
maxHeap.Insert(queue.Dequeue());
}
}
return(sb.Length == str.Length ? sb.ToString() : "");
}
// create a dictionary with character and frequency
// Create a MaxHeap
// get the top element add to the string and decrement the count
// do not push it back get the next element ,
// push the previous string back to heap if count >0 and heap is not empty
static string RearrangeString(string str)
{
Dictionary <char, int> dict = new Dictionary <char, int>();
foreach (char c in str)
{
if (!dict.ContainsKey(c))
{
dict.Add(c, 0);
}
dict[c]++;
}
MaxHeap maxHeap = new MaxHeap(dict.Count);
foreach (var entry in dict)
{
maxHeap.Insert(new Element(entry.Key, entry.Value));
}
Element previous = null;
Element current = null;
StringBuilder sb = new StringBuilder();
while (maxHeap.Count > 0)
{
current = maxHeap.Delete();
if (previous != null && previous.Frequency > 0)
{
maxHeap.Insert(previous);
}
sb.Append(current.Character);
current.Frequency--;
previous = current;
}
return(sb.Length == str.Length ? sb.ToString() : "");
}
