[Hacker Rank] Interview Preparation Kit: Miscellaneous: Flipping bits. Solved ✓.

Author: Gonzalo Diaz

docs/hackerrank/interview_preparation_kit/miscellaneous/flipping-bits.md

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+# [Miscellaneous: Flipping bits](https://www.hackerrank.com/challenges/flipping-bits)
+
+- Difficulty:  `#easy`
+- Category: `#ProblemSolvingBasic` `#BitManipulation`
+
+You will be given a list of 32 bit unsigned integers.
+Flip all the bits ( `1 -> 0` and `0 -> 1`)
+and return the result as an unsigned integer.
+
+## Example
+
+$ n = 9_{10} $. We're working with 32 bits, so:
+
+$ 9_{10} = 1001_{2} $
+
+$ 00000000000000000000000000001001_{2} = 9_{10} $
+$ 11111111111111111111111111110110_{2} = 4294967286_{10} $
+
+Return `4294967286`
+
+## Function Description
+
+Complete the flippingBits function in the editor below.
+
+flippingBits has the following parameter(s):
+
+- `int n`: an integer
+
+## Returns
+
+- `int`: the unsigned decimal integer result
+
+## Input Format
+
+The first line of the input contains `q`, the number of queries.
+Each of the next `q` lines contain an integer, `n`, to process.
+
+## Constraints
+
+- $ 1 \leq q \leq 100 $
+- $ 0 \leq n \leq 2^{32} $
+
+## Sample Input 0
+
+```text
+3
+2147483647
+1
+0
+```
+
+## Sample Output 0
+
+```text
+2147483648
+4294967294
+4294967295
+```
+
+## Explanation 0
+
+$ 01111111111111111111111111111111_{2} = 2147483647_{10} $
+$ 10000000000000000000000000000000_{2} = 2147483648_{10} $
+
+$ 00000000000000000000000000000001_{2} = 1_{10} $
+$ 11111111111111111111111111111110_{2} = 4294967294_{10} $
+
+$ 00000000000000000000000000000000_{2} = 0_{10} $
+$ 11111111111111111111111111111110_{2} = 4294967295_{10} $
+
+## Sample Input 1
+
+```text
+2
+4
+123456
+```
+
+## Sample Output 1
+
+```text
+4294967291
+4294843839
+```
+
+## Explanation 1
+
+$ 00000000000000000000000000000100_{2} = 4_{10} $
+$ 11111111111111111111111111111011_{2} = 4294967291_{10} $
+
+$ 00000000000000011110001001000000_{2} = 4_{10} $
+$ 11111111111111100001110110111111_{2} = 429484389_{10} $
+
+## Sample Input 2
+
+```text
+3
+0
+802743475
+35601423
+```
+
+## Sample Output 2
+
+```text
+4294967295
+3492223820
+4259365872
+```
+
+## Explanation 2
+
+$ 00000000000000000000000000000000_{2} = 4_{10} $
+$ 11111111111111111111111111111111_{2} = 4294967295_{10} $
+
+$ 00101111110110001110010010110011_{2} = 802743475_{10} $
+$ 11010000001001110001101101001100_{2} = 3492223820_{10} $
+
+$ 00000010000111110011110000001111_{2} = 35601423_{10} $
+$ 11111101111000001100001111110000_{2} = 4259365872_{10} $

src/algorithm_exercises_csharp/hackerrank/interview_preparation_kit/miscellaneous/FlippingBits.cs

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+// @link Problem definition [[docs/hackerrank/interview_preparation_kit/miscellaneous/flipping-bits.md]]
+
+namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.miscellaneous;
+
+using System.Diagnostics.CodeAnalysis;
+
+public static class FlippingBits
+{
+
+  public static long flippingBits(long n)
+  {
+    string n_bin_str = Convert.ToString(n, 2);
+    n_bin_str = n_bin_str.PadLeft(32, '0'); // Ensure 32 bits
+    string result_bin_str = "";
+
+    foreach (char bin_digit in n_bin_str)
+    {
+      if (bin_digit == '1')
+      {
+        result_bin_str = result_bin_str + '0';
+      }
+      else
+      {
+        result_bin_str = result_bin_str + '1';
+      }
+    }
+
+    long number = Convert.ToUInt32(result_bin_str, 2);
+
+    return number;
+  }
+}

src/algorithm_exercises_csharp_test/Resources/hackerrank/interview_preparation_kit/miscellaneous/flipping_bits.testcases.json

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+[
+  {
+    "title": "Sample Test Case 0",
+    "tests": [
+      {
+        "input": 2147483647,
+        "answer": 2147483648
+      },
+      {
+        "input": 1,
+        "answer": 4294967294
+      },
+      {
+        "input": 0,
+        "answer": 4294967295
+      }
+    ]
+  },
+  {
+    "title": "Sample Test Case 1",
+    "tests": [
+      {
+        "input": 4,
+        "answer": 4294967291
+      },
+      {
+        "input": 123456,
+        "answer": 4294843839
+      }
+    ]
+  },
+  {
+    "title": "Sample Test Case 2",
+    "tests": [
+      {
+        "input": 0,
+        "answer": 4294967295
+      },
+      {
+        "input": 802743475,
+        "answer": 3492223820
+      },
+      {
+        "input": 35601423,
+        "answer": 4259365872
+      }
+    ]
+  }
+]

src/algorithm_exercises_csharp_test/hackerrank/interview_preparation_kit/miscellaneous/FlippingBits.Test.cs

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+namespace algorithm_exercises_csharp_test.hackerrank.interview_preparation_kit.miscellaneous;
+
+using algorithm_exercises_csharp_test.common;
+using algorithm_exercises_csharp.hackerrank.interview_preparation_kit.miscellaneous;
+
+[TestClass]
+public class FlippingBitsTest
+{
+  public class FlippingBitsTestCaseTest(long input, long answer)
+  {
+    public long Input { get; } = input;
+    public long Answer { get; } = answer;
+  }
+
+  public class FlippingBitsTestCase(string title, List<FlippingBitsTestCaseTest> tests)
+  {
+    public string Title { get; } = title;
+    public List<FlippingBitsTestCaseTest> Tests { get; } = tests;
+  }
+
+  private List<FlippingBitsTestCase> testCases { get; set; } = default!;
+
+  [TestInitialize]
+  public void testInitialize()
+  {
+    testCases = JsonLoader.resourceLoad<List<FlippingBitsTestCase>>(
+      "hackerrank/interview_preparation_kit/miscellaneous/flipping_bits.testcases.json"
+    ) ?? [];
+  }
+
+  [TestMethod]
+  public void testFlippingBits()
+  {
+    long result;
+
+    foreach (FlippingBitsTestCase tests in testCases)
+    {
+      foreach (FlippingBitsTestCaseTest test in tests.Tests)
+      {
+        result = FlippingBits.flippingBits(test.Input);
+        Assert.AreEqual(
+          test.Answer,
+          result,
+          string.Format(
+            System.Globalization.CultureInfo.InvariantCulture,
+            "FlippingBits.flippingBits({0}) => must be: {1}",
+            test.Input,
+            test.Answer
+          )
+        );
+      }
+    }
+  }
+}