public int minDeletionsToMakeFrequencyOfEachLetterUnique(string s)
{
// counter of characters to delete
int count = 0;
// array of counters of occurrences for all possible characters
Dictionary <char, int> freq = new Dictionary <char, int>();
foreach (char c in s)
{
if (freq.ContainsKey(c))
{
freq[c]++;
}
else
{
freq.Add(c, 1);
}
}
var heap = new C5.IntervalHeap <int>();
heap.AddAll(freq.Select(i => i.Value));
while (heap.Count > 0)
{
// take the biggest frequency of a character
int most_frequent = heap.FindMax();
heap.DeleteMax();
if (heap.Count == 0)
{
return(count);
}
// if this frequency is equal to the next one
// and bigger than 1 decrease it to 1 and put
// back to the queue
if (most_frequent == heap.FindMax())
{
if (most_frequent > 1)
{
heap.Add(most_frequent - 1);
}
count++;
}
// all frequencies which are bigger than
// the next one are removed from the queue
// because they are unique
}
return(count);
}
public CustomWeightedGraph MinimumSpanTree()
{
// Prim's Algorithm
var minSpanTree = new CustomWeightedGraph();
var totalNodes = GetTotalNodes();
var nodes = new HashSet <Node>();
var edgesPriorityQueue = new C5.IntervalHeap <Edge>(new EdgeComp());
if (itemsMap.Count == 0)
{
return(minSpanTree); // Error Handling
}
var node = itemsMap.Values.First(); // Randomly pick the first node to add to Minimum Span Tree
nodes.Add(node);
minSpanTree.AddNode(node.label);
edgesPriorityQueue.AddAll(node.GetEdges());
while (nodes.Count < totalNodes)
{
var minEdge = edgesPriorityQueue.DeleteMax();
if (minSpanTree.ContainNode(minEdge.to.label) && minSpanTree.ContainNode(minEdge.from.label))
{
continue;
}
node = minEdge.to;
nodes.Add(node);
minSpanTree.AddNode(node.label);
minSpanTree.AddEdge(minEdge.from.label, minEdge.to.label, minEdge.weight);
edgesPriorityQueue.AddAll(node.GetEdges().Where(e => !minSpanTree.ContainNode(e.to.label)));
}
return(minSpanTree);
}
public void C5_IntervalHeap() => c5_intervalheap.AddAll(Items);
