public static List <String> topMentioned(int k, List <String> keywords, List <String> reviews)
{
List <string> result = new List <string>();
//:? non capturing expression
//\\b \\b match a block of word not word part of other string or punctuation;
string s = "\\b(:?" + String.Join("|", keywords) + ")\\b";
Regex r = new Regex(s, RegexOptions.IgnoreCase);
Dictionary <string, int> dict = new Dictionary <string, int>();
foreach (string review in reviews)
{
MatchCollection matches = r.Matches(review);
HashSet <string> words = new HashSet <string>();
foreach (Match m in matches)
{
words.Add(m.Value.ToLower());
}
foreach (string w in words)
{
if (!dict.ContainsKey(w))
{
dict.Add(w, 1);
}
else
{
dict[w]++;
}
}
}
PQ <string> pq = new PQ <string>(Comparer <string> .Create((a, b) => (dict[a] == dict[b])? a.CompareTo(b): dict[a] - dict[b]));
foreach (var item in dict)
{
if (pq.Count() < k)
{
pq.Enqueue(item.Key);
}
else
{
if (item.Value > dict[pq.Peek()])
{
pq.Dequeue();
pq.Enqueue(item.Key);
}
}
}
while (pq.Count() != 0)
{
result.Insert(0, pq.Dequeue());
}
return(result);
}
//For input of size n and output of size m, this approach takes O(n + m log n)
//Space complexity O(m)
public static List <int> GetBoxWeight(List <int> weights)
{
//[3,7,5,6,2] sum=23
// 23/2 = 11
//Heap
// 7
// 6 5
//3 2
int target = weights.Sum() / 2;
PQ <int> pq = new PQ <int>(false);
pq.AddAll(weights.ToArray());
int curSum = 0;
List <int> res = new List <int>();
while (curSum <= target)
{
int val = pq.Dequeue();
curSum += val;
res.Insert(0, val);
}
return(res);
}