public int FourSumCount(int[] A, int[] B, int[] C, int[] D)
{
var dict = new ItemCountDictionary <int>();
for (var i = 0; i < A.Length; ++i)
{
for (var j = 0; j < B.Length; ++j)
{
dict[A[i] + B[j]]++;
}
}
var count = 0;
for (var k = 0; k < C.Length; ++k)
{
for (var l = 0; l < D.Length; ++l)
{
var sum = C[k] + D[l];
if (dict[0 - sum] > 0)
{
count += dict[0 - sum];
}
}
}
return(count);
}
public int[] TopKFrequent(int[] nums, int k)
{
var dict = new ItemCountDictionary <int>();
foreach (var num in nums)
{
dict[num]++;
}
var queue = new PriorityQueue <KeyValuePair <int, int> >(200, new ItemFrequencyComparer());
foreach (var kvPair in dict)
{
queue.Push(kvPair);
if (queue.Count > k)
{
queue.Pop();
}
}
var result = new int[k];
var index = 0;
while (queue.Count > 0)
{
var node = queue.Pop();
result[index++] = node.Key;
}
return(result);
}
public bool CanConstruct(string ransomNote, string magazine)
{
var magazineDict = new ItemCountDictionary <Char>();
for (var i = 0; i < magazine.Length; ++i)
{
var c = magazine[i];
magazineDict[c]++;
}
var ransomNoteDict = new ItemCountDictionary <Char>();
for (var i = 0; i < ransomNote.Length; ++i)
{
var c = ransomNote[i];
ransomNoteDict[c]++;
}
foreach (var entry in ransomNoteDict)
{
if (!magazineDict.ContainsKey(entry.Key) ||
ransomNoteDict[entry.Key] > magazineDict[entry.Key])
{
return(false);
}
}
return(true);
}
public LFUCache(int capacity)
{
_keyToValue = new Dictionary <int, int>();
_keyToFreq = new ItemCountDictionary <int>();
_freqToKeys = new Dictionary <int, List <int> >();
_capacity = capacity;
_minFreq = 0;
}
