I would like to get the bare minimum amount of words that would be needed to create a collection of strings. For example:

"hi hello hello", "hello", "bye", "bye bye", "hello hello",

The intended output for this example would be string[] {"bye", "bye", "hello", "hello", "hi"} in no particular order.

I did a string.Join() on the starting array, and I wanted to use a HashSet to get the unique strings, but for some reason I couldn’t import it.

My goal was to get the highest count for each word, and then duplicate each word into the final string array.

CodePudding user response：

1. Split each string into words, then group same words together.

// (hi), (hello hello)
// (hello)
// (bye)
// (bye bye)
// (hello hello)
var strs = new string[]{"hi hello hello", "hello","bye", "bye bye", "hello hello"};
var result = strs.Select(str => str.Split(' ').GroupBy(word => word))

2. Flatten the groups and count the occurrence

// hi => 1
// hello => 2
// hello => 1
// bye => 1
// bye => 2
// hello => 2
.SelectMany(groups => groups)
.Select(group => KeyValuePair.Create(group.Key, group.Count()))

3. Group the results again and find the highest count of each group, use Enumerable.Repeat to generate duplicates for each word.

// hi => 1
// hello => 2, hello => 1, hello => 2
// bye => 1, bye => 2
.GroupBy(group => group.Key)
.SelectMany(group => Enumerable.Repeat(group.Key, group.Max(g => g.Value)))
.ToArray();

CodePudding user response：

Here's an example. I first get a list of distinct words in each of the original strings. Then I check each of the original strings for the number of times each of the distinct word appears. The number of times the word occurs is recorded to a dictionary. And finally, we loop through the dictionary and repeat each of the words we found by the number of time we found an occurance of the word.

string[] strList = new string[] { "hi hello hello", "hello", "bye", "bye bye", "hello hello" };

List<string> wordList = new List<string>();

//Break each string into an array of words.
foreach (string s in strList) {
    wordList.AddRange(s.Split(' '));
}

//Get a list of distinct words.
List<string> distinctWords = wordList.Distinct().ToList();

//Dictionary to hold the minimal count of words required to comprise the original strings
Dictionary<string, int> wordMinCountDict = new Dictionary<string, int>();

//Loop through each distinct word.
//Find the number of times it occurs in each of the original strings.
//Collect the highest count of the number of times the word occurs in the string.
foreach(string w in distinctWords)
{
    foreach(string s in strList)
    {
        int instanceCount = s.Split(' ').ToList().FindAll(p => p == w).Count();
        if (instanceCount > 0)
        {
            if (wordMinCountDict.TryGetValue(w, out int i))
            {
                if (instanceCount > i)
                {
                    wordMinCountDict.Remove(w);
                    wordMinCountDict.Add(w, instanceCount);
                }
            }
            else
            {
                wordMinCountDict.Add(w, instanceCount);
            }
        }
    }
}

//Create a new list with the number of occurrences of each word.
List<string> finalWords = new List<string>();
foreach(KeyValuePair<string, int> kvp in wordMinCountDict)
{
    if (kvp.Value < 1) continue;
    finalWords.AddRange(Enumerable.Repeat(kvp.Key, kvp.Value).ToList());
}

//Use .ToArray() to convert finalWords to final array. (not neccessary in the next statement but left in as an example.)
Console.WriteLine(string.Join(" ", finalWords.ToArray()));