Calculate middle (#109)

realDuYuanChao · github-actions · web-flow · commit 0db265e00c1d · 2021-04-21T09:33:59.000+08:00
* middle index calculate

* Formatted with Google Java Formatter

Co-authored-by: github-actions &lt;${GITHUB_ACTOR}@users.noreply.github.com&gt;
diff --git a/src/main/java/com/examplehub/maths/MiddleIndexCalculate.java b/src/main/java/com/examplehub/maths/MiddleIndexCalculate.java
@@ -0,0 +1,15 @@
+package com.examplehub.maths;
+
+public class MiddleIndexCalculate {
+
+  /**
+   * Return middle index from left index to right index.
+   *
+   * @param left the left index of array.
+   * @param right the right index of array.
+   * @return middle index.
+   */
+  public static int middle(int left, int right) {
+    return (left + right) >>> 1;
+  }
+}
diff --git a/src/test/java/com/examplehub/maths/MiddleIndexCalculateTest.java b/src/test/java/com/examplehub/maths/MiddleIndexCalculateTest.java
@@ -0,0 +1,18 @@
+package com.examplehub.maths;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class MiddleIndexCalculateTest {
+  @Test
+  void testMiddle() {
+    assertEquals(0, MiddleIndexCalculate.middle(0, 1));
+    assertEquals(5, MiddleIndexCalculate.middle(0, 10));
+    assertEquals(
+        Integer.MAX_VALUE - 1,
+        MiddleIndexCalculate.middle(Integer.MAX_VALUE - 1, Integer.MAX_VALUE));
+    assertEquals(
+        Integer.MAX_VALUE, MiddleIndexCalculate.middle(Integer.MAX_VALUE, Integer.MAX_VALUE));
+  }
+}
