Merge pull request #344 from sir-gon/feature/minimum_absolute_difference_in_an_array

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

Author: sir-gon

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$.

exercises/hackerrank/interview_preparation_kit/greedy_algorithms/minimum_absolute_difference_in_an_array.go

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+/**
+ * @link Problem definition
+ * [[docs/hackerrank/interview_preparation_kit/greedy_algorithms/minimum-absolute-difference-in-an-array.md]]
+ */
+
+package hackerrank
+
+import "slices"
+
+func minimumAbsoluteDifference(arr []int32) int32 {
+	// Sort the array
+	arrCopy := make([]int32, len(arr))
+
+	copy(arrCopy, arr)
+	slices.Sort(arrCopy)
+
+	// Find the minimum absolute difference
+	result := int32(0)
+	for i := range len(arrCopy) - 1 {
+		diff := arrCopy[i+1] - arrCopy[i]
+		if diff < result || result == 0 {
+			result = diff
+		}
+	}
+	return result
+}
+
+func MinimumAbsoluteDifferenceInAnArray(arr []int32) int32 {
+	return minimumAbsoluteDifference(arr)
+}

exercises/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
+  }
+]

exercises/hackerrank/interview_preparation_kit/greedy_algorithms/minimum_absolute_difference_in_an_array_test.go

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+package hackerrank
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"gon.cl/algorithms/utils"
+)
+
+type MinimumAbsoluteDifferenceInAnArrayTestCase struct {
+	Input    []int32 `json:"input"`
+	Expected int32   `json:"expected"`
+}
+
+var MinimumAbsoluteDifferenceInAnArrayTestCases []MinimumAbsoluteDifferenceInAnArrayTestCase
+
+// You can use testing.T, if you want to test the code without benchmarking
+func MinimumAbsoluteDifferenceInAnArraySetupSuite(t testing.TB) {
+	wd, _ := os.Getwd()
+	filepath := wd + "/minimum_absolute_difference_in_an_array.testcases.json"
+	t.Log("Setup test cases from JSON: ", filepath)
+
+	var _, err = utils.LoadJSON(filepath, &MinimumAbsoluteDifferenceInAnArrayTestCases)
+	if err != nil {
+		t.Log(err)
+	}
+}
+
+func TestMinimumAbsoluteDifferenceInAnArray(t *testing.T) {
+
+	MinimumAbsoluteDifferenceInAnArraySetupSuite(t)
+
+	for _, tt := range MinimumAbsoluteDifferenceInAnArrayTestCases {
+		testname := fmt.Sprintf("MinimumAbsoluteDifferenceInAnArray(%v) => %v \n", tt.Input, tt.Expected)
+		t.Run(testname, func(t *testing.T) {
+			ans := MinimumAbsoluteDifferenceInAnArray(tt.Input)
+			assert.Equal(t, tt.Expected, ans)
+		})
+	}
+}