Next greater element (examplehub#43)

realDuYuanChao · github-actions · web-flow · commit ef11c7a855bd · 2020-10-31T12:07:25.000+08:00
* fixed typo

* next greater element

* Formatted with Google Java Formatter

Co-authored-by: github-actions &lt;${GITHUB_ACTOR}@users.noreply.github.com&gt;
diff --git a/src/test/java/com/examplehub/datastructures/stack/ExpressionEvaluationTest.java b/src/test/java/com/examplehub/datastructures/stack/ExpressionEvaluationTest.java
@@ -8,10 +8,10 @@ class ExpressionEvaluationTest {
 
   @Test
   void evaluate() throws Exception {
-    assertEquals(5, 2 + 3);
-    assertEquals(-1, 2 - 3);
-    assertEquals(0, 2 / 3);
-    assertEquals(6, 2 * 3);
+    assertEquals(5, ExpressionEvaluation.evaluate("2 + 3"));
+    assertEquals(-1, ExpressionEvaluation.evaluate("2 - 3"));
+    assertEquals(0, ExpressionEvaluation.evaluate("2 / 3"));
+    assertEquals(6, ExpressionEvaluation.evaluate("2 * 3"));
     assertEquals(80, ExpressionEvaluation.evaluate("1+(2*3^4)/2-2"));
     assertEquals(80, ExpressionEvaluation.evaluate("1 + (2 * 3 ^ 4) / 2 - 2"));
   }
diff --git a/src/test/java/com/examplehub/maths/NextGreaterElement.java b/src/test/java/com/examplehub/maths/NextGreaterElement.java
@@ -0,0 +1,24 @@
+package com.examplehub.maths;
+
+public class NextGreaterElement {
+
+  /**
+   * Calculate next greater element of array.
+   *
+   * @param array the array to be searched.
+   * @return next greater element array.
+   */
+  public static int[] nextGreater(int[] array) {
+    for (int i = 0; i < array.length; i++) {
+      int nextGreater = -1;
+      for (int j = i + 1; j < array.length; j++) {
+        if (array[j] > array[i]) {
+          nextGreater = array[j];
+          break;
+        }
+      }
+      array[i] = nextGreater;
+    }
+    return array;
+  }
+}
diff --git a/src/test/java/com/examplehub/maths/NextGreaterElementTest.java b/src/test/java/com/examplehub/maths/NextGreaterElementTest.java
@@ -0,0 +1,15 @@
+package com.examplehub.maths;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.Arrays;
+import org.junit.jupiter.api.Test;
+
+class NextGreaterElementTest {
+  @Test
+  void test() {
+    assertEquals(
+        Arrays.toString(new int[] {5, -1, 4, 5, -1}),
+        Arrays.toString(NextGreaterElement.nextGreater(new int[] {2, 5, 3, 4, 5})));
+  }
+}
