Merge pull request #314 from sir-gon/feature/minimum-absolute-difference-in-an-array

[Hacker Rank] Interview Preparation Kit: Greedy Algorithms: Minimum A…

Author: sir-gon

algorithm-exercises-java/src/main/java/ae/hackerrank/interview_preparation_kit/greedy_algorithms/MinimumAbsoluteDifferenceInAnArray.java

@@ -0,0 +1,45 @@
+package ae.hackerrank.interview_preparation_kit.greedy_algorithms;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * MinimumAbsoluteDifferenceInAnArray.
+ *
+ * @link Problem definition
+ *       [[docs/hackerrank/interview_preparation_kit/greedy_algorithms/minimum-absolute-difference-in-an-array.md]]
+ */
+public class MinimumAbsoluteDifferenceInAnArray {
+
+  private MinimumAbsoluteDifferenceInAnArray() {
+  }
+
+  /**
+   * minimumAbsoluteDifference.
+   */
+  public static int minimumAbsoluteDifference(List<Integer> arr) {
+    List<Integer> sortedNums = arr.stream().collect(Collectors.toList());
+    Collections.sort(sortedNums);
+
+    // Find the minimum absolute difference
+    int result = 0;
+    boolean resultEmpty = true;
+
+    for (int i = 0; i < sortedNums.size() - 1; i++) {
+      int aValue = sortedNums.get(i);
+      int bValue = sortedNums.get(i + 1);
+
+      int diff = Math.abs(aValue - bValue);
+
+      if (resultEmpty) {
+        result = diff;
+        resultEmpty = false;
+      } else {
+        result = Math.min(result, diff);
+      }
+    }
+
+    return result;
+  }
+}

algorithm-exercises-java/src/test/java/ae/hackerrank/interview_preparation_kit/greedy_algorithms/MinimumAbsoluteDifferenceInAnArrayTest.java

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+package ae.hackerrank.interview_preparation_kit.greedy_algorithms;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.IOException;
+import java.util.List;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.TestInstance.Lifecycle;
+import util.JsonLoader;
+
+/**
+ * MinimumAbsoluteDifferenceInAnArrayTest.
+ */
+@TestInstance(Lifecycle.PER_CLASS)
+class MinimumAbsoluteDifferenceInAnArrayTest {
+  public static class MinimumAbsoluteDifferenceInAnArrayTestCase {
+    public String title;
+    public List<Integer> input;
+    public Integer expected;
+  }
+
+  private List<MinimumAbsoluteDifferenceInAnArrayTestCase> testCases;
+
+  @BeforeAll
+  void setup() throws IOException {
+    String path = String.join("/",
+        "hackerrank",
+        "interview_preparation_kit",
+        "greedy_algorithms",
+        "minimum_absolute_difference_in_an_array.testcases.json");
+    this.testCases = JsonLoader.loadJson(path, MinimumAbsoluteDifferenceInAnArrayTestCase.class);
+  }
+
+  @Test
+  void testLuckBalance() {
+    for (MinimumAbsoluteDifferenceInAnArrayTestCase test : testCases) {
+      Integer result = MinimumAbsoluteDifferenceInAnArray.minimumAbsoluteDifference(test.input);
+
+      assertEquals(test.expected, result,
+          "%s(%s) => must be: %d".formatted(
+              "MinimumAbsoluteDifferenceInAnArray.minimumAbsoluteDifference",
+              test.input.toString(),
+              test.expected));
+    }
+  }
+}

algorithm-exercises-java/src/test/resources/hackerrank/interview_preparation_kit/greedy_algorithms/minimum_absolute_difference_in_an_array.testcases.json

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+[
+  {
+    "title": "Sample Test case 0",
+    "input": [3, -7, 0],
+    "expected": 3
+  },
+  {
+    "title": "Sample Test case 1",
+    "input": [-59, -36, -13, 1, -53, -92, -2, -96, -54, 75],
+    "expected": 1
+  },
+  {
+    "title": "Sample Test case 2",
+    "input": [1, -3, 71, 68, 17],
+    "expected": 3
+  }
+]

docs/hackerrank/interview_preparation_kit/greedy_algorithms/minimum-absolute-difference-in-an-array.md

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+# [Minimum Absolute Difference in an Array](https://www.hackerrank.com/challenges/minimum-absolute-difference-in-an-array)
+
+- Difficulty:  `#medium`
+- Category: `#ProblemSolvingBasic` `#greedyalgorithms`
+
+The absolute difference is the positive difference between two
+values `a` and `b`, is written $ \lvert a - b \rvert $
+or $ \lvert b - a \rvert $
+and they are equal. If `a = 3` and `b = 2`, $ \lvert 3 - 2 \rvert =
+\lvert 2 - 3 \rvert = 1 $.
+Given an array of integers, find the minimum absolute difference
+between any two elements in the array.
+
+**Example** `arr = [-2, 2, 4]`6
+
+There are  pairs of numbers: `[-2, 2]`, `[-2, 4]` and `[2, 4]`.
+The absolute differences for these pairs are
+$ \lvert (-2) - 2 \rvert = 4 $, $ \lvert (-2) - 4 \rvert = 6 $ and
+$ \lvert 2 - 4 \rvert = 2 $.
+The minimum absolute difference is `2`.
+
+## Function Description
+
+Complete the minimumAbsoluteDifference function in the editor below.
+It should return an integer that represents the minimum absolute difference
+between any pair of elements.
+
+minimumAbsoluteDifference has the following parameter(s):
+
+- `int arr[n]`: an array of integers
+
+## Returns
+
+int: the minimum absolute difference found
+
+## Input Format
+
+The first line contains a single integer , the size of .
+The second line contains  space-separated integers, .
+
+## Constraints
+
+- $ 2 \leq n \leq 10^5 $
+- $ -10^9 \leq arr[i] \leq 10^9 $
+
+## Sample Input 0
+
+```text
+3
+3 -7 0
+```
+
+## Sample Output 0
+
+```text
+3
+```
+
+## Explanation 0
+
+The first line of input is the number of array elements. The array,
+ `arr = [3, -7, 0]`
+There are three pairs to test: `(3, -7)`, `(3, 0)`, and `(-7, 0)`.
+The absolute differences are:
+
+- $ \lvert 3 - -7 \rvert => 10 $
+- $ \lvert 3 - 0 \rvert => 3 $
+- $ \lvert -7 - 0 \rvert => 7 $
+
+Remember that the order of values in
+the subtraction does not influence the result.
+The smallest of these absolute differences is `3`.
+
+## Sample Input 1
+
+```text
+10
+-59 -36 -13 1 -53 -92 -2 -96 -54 75
+```
+
+## Sample Output 1
+
+```text
+1
+```
+
+## Explanation 1
+
+The smallest absolute difference is $ \lvert - 54 - -53 \rvert = 1$.
+
+## Sample Input 2
+
+```text
+5
+1 -3 71 68 17
+```
+
+## Sample Output 2
+
+```text
+3
+```
+
+## Explanation 2
+
+The minimum absolute difference is $ \lvert - 71 - 68 \rvert = 3$.