Add "Find max consecutive elements in array" task

anverbogatov · anverbogatov · commit 5313498c748c · 2022-07-08T08:14:26.000+04:00
diff --git a/src/main/java/com/anverbogatov/algorithms/tasks/README.md b/src/main/java/com/anverbogatov/algorithms/tasks/README.md
@@ -20,4 +20,10 @@ For example, given [10, 15, 3, 7] and k of 17, return true since 10 + 7 is 17.
 
 Implement algorithm that shows if all characters in a given string are unique.
 
-**Bonus**: What if you are not allowed to use other data structures?
+**Bonus**: What if you are not allowed to use other data structures?
+
+## 📗 Task #3
+
+In the given array of numbers find max amount of consecutive elements.
+
+For example, given [10, 15, 2, 2, 2, 3, 7] max amount of consecutive elements will be equal to 3.
diff --git a/src/main/java/com/anverbogatov/algorithms/tasks/Task3.java b/src/main/java/com/anverbogatov/algorithms/tasks/Task3.java
@@ -0,0 +1,38 @@
+package com.anverbogatov.algorithms.tasks;
+
+import java.util.HashSet;
+
+public final class Task3 {
+
+    /**
+     * Calculate amount of consecutive elements in a given array.
+     *
+     * @param arr - array that need to be checked
+     * @return number of consecutive elements
+     */
+    public static int maxAmountOfConsecutiveElements(int[] arr) {
+        if (arr == null || arr.length == 0) {
+            return 0;
+        }
+
+        if (arr.length == 1) {
+            return 1;
+        }
+
+        int result = 0;
+        int leftIndex = 0;
+
+        for (; leftIndex < arr.length - 1; leftIndex++) {
+            int rightIndex = leftIndex;
+
+            for (; rightIndex < arr.length; rightIndex++) {
+                if (arr[leftIndex] != arr[rightIndex]) {
+                    break;
+                }
+            }
+
+            result = Math.max(result, rightIndex - leftIndex);
+        }
+        return result;
+    }
+}
diff --git a/src/test/java/com/anverbogatov/algorithms/tasks/Task3Test.java b/src/test/java/com/anverbogatov/algorithms/tasks/Task3Test.java
@@ -0,0 +1,23 @@
+package com.anverbogatov.algorithms.tasks;
+
+import junit.framework.TestCase;
+import org.junit.Assert;
+
+public class Task3Test extends TestCase {
+
+    public void testNull() {
+        Assert.assertEquals(0, Task3.maxAmountOfConsecutiveElements(null));
+    }
+
+    public void testSingleElement() {
+        Assert.assertEquals(1, Task3.maxAmountOfConsecutiveElements(new int[]{1}));
+    }
+
+    public void testAlgorithmWithSingleSequence() {
+        Assert.assertEquals(3, Task3.maxAmountOfConsecutiveElements(new int[]{10, 15, 2, 2, 2, 3, 7}));
+    }
+
+    public void testAlgorithmWithMultipleSequence() {
+        Assert.assertEquals(4, Task3.maxAmountOfConsecutiveElements(new int[]{10, 15, 2, 2, 2, 3, 7, 1, 1, 7, 7, 7, 7, 11, 2, -4}));
+    }
+}
