[Hacker Rank] Interview Preparation Kit: Arrays: New Year Chaos. Solv…

algorithm_exercises_csharp/src/hackerrank/interview_preparation_kit/arrays/NewYearChaos.cs

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+namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit;
+
+using System.Diagnostics.CodeAnalysis;
+
+
+/**
+ * New Year Chaos.
+ *
+ * @link Problem definition [[docs/hackerrank/interview_preparation_kit/arrays/new_year_chaos.md]]
+ */
+public class NewYearChaos
+{
+  [ExcludeFromCodeCoverage]
+  protected NewYearChaos() { }
+
+  public const String TOO_CHAOTIC_ERROR = "Too chaotic";
+
+  /**
+   * minimumBribesCalculate.
+   */
+  public static int minimumBribesCalculate(List<int> q)
+  {
+    int bribes = 0;
+    int i = 0;
+
+    foreach (int value in q)
+    {
+      int position = i + 1;
+
+      if (value - position > 2)
+      {
+        throw new InvalidOperationException(TOO_CHAOTIC_ERROR);
+      }
+
+      List<int> fragment = q[Math.Min(Math.Max(value - 2, 0), i)..i];
+
+      foreach (int k in fragment)
+      {
+        if (k > value)
+        {
+          bribes += 1;
+        }
+      }
+      i += 1;
+    }
+
+    return bribes;
+  }
+
+  /**
+   * minimumBribes.
+   */
+  public static String minimumBribesText(List<int> q)
+  {
+    try
+    {
+      int bribes = minimumBribesCalculate(q);
+      return String.Format("{0}", bribes);
+    }
+    catch (InvalidOperationException e)
+    {
+      return String.Format(e.Message);
+    }
+  }
+
+  /**
+   * minimumBribesText.
+   */
+  public static void minimumBribes(List<int> q)
+  {
+    Console.WriteLine("{0}", minimumBribesText(q));
+  }
+}

algorithm_exercises_csharp_test/Resources/hackerrank/interview_preparation_kit/arrays/new_year_chaos.testcases.json

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+[
+    {
+      "title": "Test Case 0-0",
+      "input": [2, 1, 5, 3, 4],
+      "expected": 3
+    },
+    {
+     "title": "Test Case 0-1",
+     "input": [2, 5, 1, 3, 4],
+     "expected": "Too chaotic"
+    },
+    {
+     "title": "Test Case 1-1",
+     "input": [5, 1, 2, 3, 7, 8, 6, 4],
+     "expected": "Too chaotic"
+    },
+    {
+      "title": "Test Case 1-2",
+      "input": [1, 2, 5, 3, 7, 8, 6, 4],
+      "expected": 7
+    },
+    {
+      "title": "Test Case 2",
+      "input": [1, 2, 5, 3, 4, 7, 8, 6],
+      "expected": 4
+    }
+  ]

algorithm_exercises_csharp_test/src/hackerrank/interview_preparation_kit/arrays/NewYearChaos.Test.cs

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+namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit;
+
+[TestClass]
+public class NewYearChaosTest
+{
+  public class NewYearChaosTestCase
+  {
+    public string title { get; set; } = default!;
+    public List<int> input { get; set; } = default!;
+    public string expected { get; set; } = default!;
+  }
+
+  private List<NewYearChaosTestCase> testCases { get; set; } = default!;
+
+  [TestInitialize]
+  public void testInitialize()
+  {
+    testCases = JsonLoader.resourceLoad<List<NewYearChaosTestCase>>(
+      "hackerrank/interview_preparation_kit/arrays/new_year_chaos.testcases.json"
+    ) ?? [];
+  }
+
+  [TestMethod]
+  public void testMinimumBribesText()
+  {
+    string result;
+
+    foreach (NewYearChaosTestCase test in testCases)
+    {
+      result = NewYearChaos.minimumBribesText(test.input);
+      NewYearChaos.minimumBribes(test.input);
+
+      Assert.AreEqual(test.expected, result);
+    }
+  }
+}
+

docs/hackerrank/interview_preparation_kit/arrays/new_year_chaos-solution-notes.md

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+# [Arrays: New Year Chaos](https://www.hackerrank.com/challenges/new-year-chaos)
+
+Determine how many bribes took place to get a queue into its current state.
+
+- Difficulty:  `#medium`
+- Category: `#ProblemSolvingBasic` `#arrays`
+
+## Solution sources
+
+- This solution focuses on "who were bribed" and counts his displacements with
+respect to those who bribed him
+(they have original position numbers greater than this one in front of him):
+[Solution to HackerRank's New Year Chaos in Python](https://csanim.com/tutorials/hackerrank-solution-new-year-chaos)
+
+- This solution focuses on the expected positions and compares whether the "briber"
+ is ahead in line: <https://www.youtube.com/watch?v=LgszjFykAbE>

docs/hackerrank/interview_preparation_kit/arrays/new_year_chaos.md

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+# [Arrays: New Year Chaos](https://www.hackerrank.com/challenges/new-year-chaos)
+
+Determine how many bribes took place to get a queue into its current state.
+
+- Difficulty:  `#medium`
+- Category: `#ProblemSolvingBasic` `#arrays`
+
+It is New Year's Day and people are in line for the Wonderland rollercoaster ride.
+Each person wears a sticker indicating their initial position in
+the queue from ` 1 ` to ` n `.
+
+Any person can bribe the person directly in front of them to swap positions,
+but they still wear their original sticker. One person can bribe at most two others.
+
+Determine the minimum number of bribes that took place to get
+to a given queue order.
+Print the number of bribes, or, if anyone has bribed more than two people,
+print ` Too chaotic `.
+
+## Example
+
+$ q = [1, 2, 3, 4, 5, 6, 7, 8] $
+
+If person ` 5 ` bribes person ` 4 `, the queue will look like this:
+$ [1, 2, 3, 5, 4, 6, 7, 8] $. Only ` 1 ` bribe is required. Print ` 1 `.
+
+$ q = [4, 1, 2, 3] $
+
+Person ` 4 ` had to bribe ` 3 ` people to get to the current position.
+Print `Too chaotic`.
+
+## Function Description
+
+Complete the function minimumBribes in the editor below.
+
+minimumBribes has the following parameter(s):
+
+- `int q[n]`: the positions of the people after all bribes
+
+## Returns
+
+- No value is returned. Print the minimum number of bribes necessary or
+ ` Too chaotic ` if someone has bribed more than  people.
+
+## Input Format
+
+The first line contains an integer ` t `, the number of test cases.
+
+Each of the next ` t `  pairs of lines are as follows:
+
+- The first line contains an integer ` t `, the number of people in the queue
+- The second line has `n` space-separated integers describing the
+final state of the queue.
+
+## Constraints
+
+- $ 1 \leq t \leq 10 $
+- $ 1 \leq n \leq 10^5 $
+
+## Subtasks
+
+For `60%` score $ 1 \leq t \leq 10^3 $
+For `100%` score $ 1 \leq t \leq 10^5 $
+
+## Sample Input
+
+```text
+STDIN       Function
+-----       --------
+2           t = 2
+5           n = 5
+2 1 5 3 4   q = [2, 1, 5, 3, 4]
+5           n = 5
+2 5 1 3 4   q = [2, 5, 1, 3, 4]
+```
+
+## Sample Output
+
+```text
+3
+Too chaotic
+```
+
+## Explanation
+
+### Test Case 1
+
+The initial state:
+
+```mermaid
+flowchart LR
+
+      A[Ride!]:::first
+      1([1])
+      2([2])
+      3([3])
+      4([4])
+      5([5])
+
+      A ~~~ 1
+      1 -.- 2
+      2 -.- 3
+      3 -.- 4
+      4 -.- 5
+
+    classDef default color:#000,fill:#FFE195,stroke:#333,stroke-width:4px;
+    classDef first fill:#9FBCE8
+    classDef emphasys fill:#FEB130
+```
+
+After person `5` moves one position ahead by bribing person `4`:
+
+```mermaid
+flowchart LR
+      A[Ride!]:::first
+      1([1])
+      2([2])
+      3([3])
+      4([4]):::emphasys
+      5([5]):::emphasys
+
+      A ~~~ 1
+      1 -.- 2
+      2 -.- 3
+      3 -.- 5
+      5 -.- 4
+
+    classDef default color:#000,fill:#FFE195,stroke:#333,stroke-width:4px;
+    classDef first fill:#9FBCE8
+    classDef emphasys fill:#FEB130
+```
+
+Now person `5` moves another position ahead by bribing person `3`:
+
+```mermaid
+flowchart LR
+      A[Ride!]:::first
+      1([1])
+      2([2])
+      3([3]):::emphasys
+      4([4])
+      5([5]):::emphasys
+
+      A ~~~ 1
+      1 -.- 2
+      2 -.- 5
+      5 -.- 3
+      3 -.- 4
+
+    classDef default color:#000,fill:#FFE195,stroke:#333,stroke-width:4px;
+    classDef first fill:#9FBCE8
+    classDef emphasys fill:#FEB130
+```
+
+And person `2` moves one position ahead by bribing person `3`:
+
+```mermaid
+flowchart LR
+      A[Ride!]:::first
+      1([1]):::emphasys
+      2([2]):::emphasys
+      3([3])
+      4([4])
+      5([5])
+
+      A ~~~ 2
+      2 -.- 1
+      1 -.- 5
+      5 -.- 3
+      3 -.- 4
+
+    classDef default color:#000,fill:#FFE195,stroke:#333,stroke-width:4px;
+    classDef first fill:#9FBCE8
+    classDef emphasys fill:#FEB130
+```
+
+So the final state is `2, 1, 5, 3, 4` after three bribing operations.
+
+### Test Case 2
+
+No person can bribe more than two people, yet it appears person `5` has done so.
+It is not possible to achieve the input state.