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29 changes: 29 additions & 0 deletions
...eparation_kit/dictionaries_and_hashmaps/sherlock_and_anagrams-solution-notes.md
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| # [Sherlock and Anagrams](https://www.hackerrank.com/challenges/sherlock-and-anagrams) | ||
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| - Difficulty: `#medium` | ||
| - Category: `#ProblemSolvingMedium` `#DictionariesAndHashmaps` `#Strings` | ||
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| ## About solution | ||
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| To answer the question of "how many pairs" of words can be anagrammed | ||
| using fragments from adjacent letters of an initial word, two steps are needed: | ||
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| 1) Obtain all possible fragment candidates to be anagrams, | ||
| from each of the possible fragments that can be generated | ||
| from adjacent letters of a word. | ||
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| 2) For each list of candidate anagrams, | ||
| calculate all possible permutations and add them up. | ||
| The total gives the answer. | ||
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| The second part of this problem can be solved with the binomial coefficient formula: | ||
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| <https://en.wikipedia.org/wiki/Binomial_coefficient> | ||
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| But the entire cost of this formula falls on the "factorial" function. | ||
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| The factorial quickly reaches results that return large numbers, | ||
| overflowing the length of primitive number types. | ||
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| To avoid this problem in C#, it is necessary to introduce large number handling | ||
| using System.Numerics.BigInteger |
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...nk/interview_preparation_kit/dictionaries_and_hashmaps/sherlock_and_anagrams.md
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| # [Sherlock and Anagrams](https://www.hackerrank.com/challenges/sherlock-and-anagrams) | ||
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| - Difficulty: `#medium` | ||
| - Category: `#ProblemSolvingMedium` `#DictionariesAndHashmaps` `#Strings` | ||
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| Two strings are [http://en.wikipedia.org/wiki/Anagram](anagrams) of each other | ||
| if the letters of one string can be rearranged to form the other string. | ||
| Given a string, find the number of pairs of substrings of the string that are | ||
| anagrams of each other. | ||
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| ## Example | ||
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| `s = mom` | ||
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| The list of all anagrammatic pairs is `[m, m]`, `[mo, om]` | ||
| at positions `[[0], [2]]`, `[[0, 1], [1, 2]]` respectively. | ||
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| ## Function Description | ||
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| Complete the function sherlockAndAnagrams in the editor below. | ||
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| *sherlockAndAnagrams* has the following parameter(s): | ||
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| - `string s`: a string | ||
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| ## Returns | ||
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| - `int`: the number of unordered anagrammatic pairs of substrings in **`s`** | ||
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| ## Input Format | ||
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| The first line contains an integer `q`, the number of queries. | ||
| Each of the next `q` lines contains a string `s` to analyze. | ||
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| ## Constraints | ||
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| - $ 1 \leq 10 \leq 10 $ | ||
| - $ 2 \leq $ lenght of `s` $ \leq 100 $ | ||
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| `s` contains only lowercase letters in the range ascii[a-z]. | ||
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| ## Sample Input 0 | ||
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| ```text | ||
| 2 | ||
| abba | ||
| abcd | ||
| ``` | ||
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| ## Sample Output 0 | ||
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| ```text | ||
| 4 | ||
| 0 | ||
| ``` | ||
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| ## Explanation 0 | ||
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| The list of all anagrammatic pairs is `[a, a]`, `[ab, ba]`, | ||
| `[b, b]` and `[abb, bba]` at positions `[[0], [3]]`, `[[0, 1]], [[2, 3]]`, | ||
| `[[1], [2]]` and `[[0, 1, 2], [1, 2, 3]]` respectively. | ||
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| No anagrammatic pairs exist in the second query as no character repeats. | ||
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| ## Sample Input 1 | ||
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| ```text | ||
| 2 | ||
| ifailuhkqq | ||
| kkkk | ||
| ```` | ||
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| ## Sample Output 1 | ||
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| ```text | ||
| 3 | ||
| 10 | ||
| ``` | ||
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| ## Explanation 1 | ||
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| For the first query, we have anagram pairs `[i, i]`, `[q, q]` | ||
| and `[ifa, fai]` at positions `[[0], [3]]`, `[[8], [9]]` | ||
| and `[[0, 1, 2], [1, 2, 3]]` respectively. | ||
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| For the second query: | ||
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| There are `6` anagrams of the form `[k, k]` at positions `[[0, 1]]`, | ||
| `[[0], [2]]`, `[[0], [3]]`, `[[1], [2]]`, `[[1], [3]]` and `[[2], [3]]`. | ||
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| There are 3 anagrams of the form `[kk, kk]` at positions `[[0, 1], [1, 2]]`, | ||
| `[[0, 1], [2, 3]]` and `[[1, 2], [2, 3]]`. | ||
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| There is 1 anagram of the form `[kkk, kkk]` at position `[[0, 1, 2], [1, 2, 3]]`. | ||
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| ## Sample Input 2 | ||
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| ```text | ||
| 1 | ||
| cdcd | ||
| ``` | ||
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| ## Sample Output 2 | ||
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| ```text | ||
| 5 | ||
| ``` | ||
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| ## Explanation 2 | ||
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| There are two anagrammatic pairs of length `1`: `[c, c]` and `[d, d]`. | ||
| There are three anagrammatic pairs of length `2`: | ||
| `[cd, dc]`, `[cd, cd]`, `[dc, cd]` at positions | ||
| `[[0, 1] [1, 2]]`, `[[0, 1], [2, 3]]`, `[1, 2], [2, 3]` respectively. |
63 changes: 63 additions & 0 deletions
...arp/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/SherlockAndAnagrams.cs
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| // @link Problem definition [[docs/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/ctci-ransom-note.md]] | ||
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| namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.dictionaries_and_hashmaps; | ||
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| using System.Diagnostics.CodeAnalysis; | ||
| using System.Numerics; | ||
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| public class SherlockAndAnagrams | ||
| { | ||
| [ExcludeFromCodeCoverage] | ||
| protected SherlockAndAnagrams() { } | ||
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| /** | ||
| * factorial(). | ||
| */ | ||
| public static BigInteger factorial(int number) | ||
| { | ||
| BigInteger result = BigInteger.One; | ||
| for (int i = 1; i <= number; i++) | ||
| { | ||
| result *= i; | ||
| } | ||
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| return result; | ||
| } | ||
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| public static int sherlockAndAnagrams(string s) | ||
| { | ||
| Dictionary<string, List<string>> candidates = []; | ||
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| int size = s.Length; | ||
| for (int i = 0; i < size; i++) | ||
| { | ||
| for (int j = 0; j < size - i; j++) | ||
| { | ||
| string word = s[i..(size - j)]; | ||
| char[] wordArray = word.ToCharArray(); | ||
| Array.Sort(wordArray); | ||
| string anagramCandidate = new(wordArray); | ||
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| if (candidates.TryGetValue(anagramCandidate, out List<string>? value)) | ||
| { | ||
| value.Add(word); | ||
| } | ||
| else | ||
| { | ||
| candidates[anagramCandidate] = [word]; | ||
| } | ||
| } | ||
| } | ||
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| int k = 2; | ||
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| int total = candidates | ||
| .Select(x => x.Value.Count) | ||
| .Where(count => count > 1) | ||
| .Sum(quantityOfAnagrams => | ||
| // Binomial coefficient: https://en.wikipedia.org/wiki/Binomial_coefficient | ||
| (int)(factorial(quantityOfAnagrams) / factorial(k) / factorial(quantityOfAnagrams - k))); | ||
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| return total; | ||
| } | ||
| } |
92 changes: 92 additions & 0 deletions
.../interview_preparation_kit/dictionaries_and_hashmaps/sherlock_and_anagrams.testcases.json
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| [ | ||
| { | ||
| "title": "Sample Test Case 0", | ||
| "tests": [ | ||
| { | ||
| "input": "abba", | ||
| "expected": 4 | ||
| }, | ||
| { | ||
| "input": "abcd", | ||
| "expected": 0 | ||
| } | ||
| ] | ||
| }, | ||
| { | ||
| "title": "Sample Test Case 1", | ||
| "tests": [ | ||
| { | ||
| "input": "ifailuhkqq", | ||
| "expected": 3 | ||
| }, | ||
| { | ||
| "input": "kkkk", | ||
| "expected": 10 | ||
| } | ||
| ] | ||
| }, | ||
| { | ||
| "title": "Sample Test Case 1", | ||
| "tests": [ | ||
| { | ||
| "input": "cdcd", | ||
| "expected": 5 | ||
| } | ||
| ] | ||
| }, | ||
| { | ||
| "title": "Test case 3", | ||
| "tests": [ | ||
| { | ||
| "input": | ||
| "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", | ||
| "expected": 166650 | ||
| }, | ||
| { | ||
| "input": | ||
| "bbcaadacaacbdddcdbddaddabcccdaaadcadcbddadababdaaabcccdcdaacadcababbabbdbacabbdcbbbbbddacdbbcdddbaaa", | ||
| "expected": 4832 | ||
| }, | ||
| { | ||
| "input": | ||
| "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", | ||
| "expected": 166650 | ||
| }, | ||
| { | ||
| "input": | ||
| "cacccbbcaaccbaacbbbcaaaababcacbbababbaacabccccaaaacbcababcbaaaaaacbacbccabcabbaaacabccbabccabbabcbba", | ||
| "expected": 13022 | ||
| }, | ||
| { | ||
| "input": | ||
| "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", | ||
| "expected": 166650 | ||
| }, | ||
| { | ||
| "input": | ||
| "bbcbacaabacacaaacbbcaabccacbaaaabbcaaaaaaaccaccabcacabbbbabbbbacaaccbabbccccaacccccabcabaacaabbcbaca", | ||
| "expected": 9644 | ||
| }, | ||
| { | ||
| "input": | ||
| "cbaacdbaadbabbdbbaabddbdabbbccbdaccdbbdacdcabdbacbcadbbbbacbdabddcaccbbacbcadcdcabaabdbaacdccbbabbbc", | ||
| "expected": 6346 | ||
| }, | ||
| { | ||
| "input": | ||
| "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", | ||
| "expected": 166650 | ||
| }, | ||
| { | ||
| "input": | ||
| "babacaccaaabaaaaaaaccaaaccaaccabcbbbabccbbabababccaabcccacccaaabaccbccccbaacbcaacbcaaaaaaabacbcbbbcc", | ||
| "expected": 8640 | ||
| }, | ||
| { | ||
| "input": | ||
| "bcbabbaccacbacaacbbaccbcbccbaaaabbbcaccaacaccbabcbabccacbaabbaaaabbbcbbbbbaababacacbcaabbcbcbcabbaba", | ||
| "expected": 11577 | ||
| } | ||
| ] | ||
| } | ||
| ] |
47 changes: 47 additions & 0 deletions
...ackerrank/interview_preparation_kit/dictionaries_and_hashmaps/SherlockAndAnagrams.Test.cs
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| namespace algorithm_exercises_csharp_test.hackerrank.interview_preparation_kit.dictionaries_and_hashmaps; | ||
| using algorithm_exercises_csharp_test.lib; | ||
| using algorithm_exercises_csharp.hackerrank.interview_preparation_kit.dictionaries_and_hashmaps; | ||
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| [TestClass] | ||
| public class SherlockAndAnagramsTest | ||
| { | ||
| public class SherlockAndAnagramsTestCase | ||
| { | ||
| /** | ||
| * SherlockAndAnagramsTestCase.TestCase. | ||
| */ | ||
| public class TestCase | ||
| { | ||
| public string input { get; set; } = default!; | ||
| public int expected { get; set; } = default!; | ||
| } | ||
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| public string title { get; set; } = default!; | ||
| public List<TestCase> tests { get; set; } = default!; | ||
| } | ||
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| private List<SherlockAndAnagramsTestCase> testCases { get; set; } = default!; | ||
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| [TestInitialize] | ||
| public void testInitialize() | ||
| { | ||
| testCases = JsonLoader.resourceLoad<List<SherlockAndAnagramsTestCase>>( | ||
| "hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/sherlock_and_anagrams.testcases.json" | ||
| ) ?? []; | ||
| } | ||
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| [TestMethod] | ||
| public void testSherlockAndAnagrams() | ||
| { | ||
| int result; | ||
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| foreach (SherlockAndAnagramsTestCase testSet in testCases) | ||
| { | ||
| foreach (SherlockAndAnagramsTestCase.TestCase test in testSet.tests) | ||
| { | ||
| result = SherlockAndAnagrams.sherlockAndAnagrams(test.input); | ||
| Assert.AreEqual(test.expected, result); | ||
| } | ||
| } | ||
| } | ||
| } |
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