Closest number to zero (#16651)

* added implementation and test

Signed-off-by: Emmanuel Mireku Omari <[email protected]>

* tests cleaned

Signed-off-by: Emmanuel Mireku Omari <[email protected]>

* formatted test

Signed-off-by: Emmanuel Mireku Omari <[email protected]>

* added parenthesis to the Bruteforce conditions

Signed-off-by: Emmanuel Mireku Omari <[email protected]>

* removed unused tests

Signed-off-by: Emmanuel Mireku Omari <[email protected]>

---------

Signed-off-by: Emmanuel Mireku Omari <[email protected]>
Signed-off-by: Emmanuel Mireku Omari <[email protected]>
Co-authored-by: Emmanuel Mireku Omari <[email protected]>

Author: 3ga01

core-java-modules/core-java-arrays-operations-advanced-2/src/main/java/com/baeldung/closesttozero/BruteForce.java

@@ -0,0 +1,18 @@
+package com.baeldung.closesttozero;
+
+public class BruteForce {
+
+    public static int findClosestToZero(int[] arr) throws IllegalAccessException {
+        if (arr == null || arr.length == 0) {
+            throw new IllegalAccessException("Array must not be null or Empty");
+        }
+
+        int closest = arr[0];
+        for (int i = 1; i < arr.length; i++) {
+            if ((Math.abs(arr[i]) < Math.abs(closest)) || ((Math.abs(arr[i]) == Math.abs(closest)) && (arr[i] > closest))) {
+                closest = arr[i];
+            }
+        }
+        return closest;
+    }
+}

core-java-modules/core-java-arrays-operations-advanced-2/src/main/java/com/baeldung/closesttozero/PriorityQueueToZero.java

@@ -0,0 +1,22 @@
+package com.baeldung.closesttozero;
+
+import java.util.PriorityQueue;
+
+public class PriorityQueueToZero {
+    public static int findClosestToZeroWithPriorityQueue(int[] arr, int k) {
+        if (arr == null || arr.length == 0 || k <= 0) {
+            throw new IllegalArgumentException("Invalid input");
+        }
+
+        PriorityQueue<Integer> pq = new PriorityQueue<>((a, b) -> Math.abs(b) - Math.abs(a));
+
+        for (int num : arr) {
+            pq.offer(num);
+            if (pq.size() > k) {
+                pq.poll();
+            }
+        }
+
+        return pq.peek();
+    }
+}

core-java-modules/core-java-arrays-operations-advanced-2/src/main/java/com/baeldung/closesttozero/SortingAndBinarySearch.java

@@ -0,0 +1,35 @@
+package com.baeldung.closesttozero;
+
+import java.util.Arrays;
+
+public class SortingAndBinarySearch {
+
+    public static int findClosestToZero(int[] arr) {
+        if (arr == null || arr.length == 0) {
+            throw new IllegalArgumentException("Array must not be null or Empty");
+        }
+
+        Arrays.sort(arr);
+        int closestNumber = arr[0];
+        int left = 0;
+        int right = arr.length - 1;
+
+        while (left <= right) {
+            int mid = left + (right - left) / 2;
+
+            if (Math.abs(arr[mid]) < Math.abs(closestNumber)) {
+                closestNumber = arr[mid];
+            }
+
+            if (arr[mid] < 0) {
+                left = mid + 1;
+            } else if (arr[mid] > 0) {
+                right = mid - 1;
+            } else {
+                return arr[mid];
+            }
+        }
+
+        return closestNumber;
+    }
+}

core-java-modules/core-java-arrays-operations-advanced-2/src/test/java/com/baeldung/closesttozero/BruteForceUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.closesttozero;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Random;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class BruteForceUnitTest {
+
+    @Test
+    void whenFindingClosestToZeroWithBruteForce_thenResultShouldBeCorrect() throws IllegalAccessException {
+        int[] arr = {11, 60, -1, 70, -11, 85};
+        assertEquals(-1, BruteForce.findClosestToZero(arr));
+    }
+}

core-java-modules/core-java-arrays-operations-advanced-2/src/test/java/com/baeldung/closesttozero/PriorityQueueTOZeroUnitTest.java

@@ -0,0 +1,16 @@
+package com.baeldung.closesttozero;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Random;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class PriorityQueueTOZeroUnitTest {
+    @Test
+    void whenFindingClosestToZeroWithBruteForce_thenResultShouldBeCorrect() throws IllegalAccessException {
+        int[] arr = {1, 60, -10, 70, -80, 85};
+        assertEquals(1, PriorityQueueToZero.findClosestToZeroWithPriorityQueue(arr, 1));
+    }
+}

core-java-modules/core-java-arrays-operations-advanced-2/src/test/java/com/baeldung/closesttozero/SortingAndBinarySearchUnitTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.closesttozero;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class SortingAndBinarySearchUnitTest {
+
+    @Test
+    void whenFindingClosestToZeroWithBruteForce_thenResultShouldBeCorrect() throws IllegalAccessException {
+        int[] arr = {1, 60, -10, 70, -80, 85};
+        assertEquals(1, SortingAndBinarySearch.findClosestToZero(arr));
+    }
+
+}