From d44f9e33f8f2ed40dbf58087532e9075890d2e90 Mon Sep 17 00:00:00 2001
From: Billy Brawner <billybrawner@gmail.com>
Date: Mon, 15 Oct 2018 18:15:11 -0500
Subject: [PATCH] Add Jump search algorithm

---
 README.md                                     |  1 +
 .../algorithms/searching/JumpSearch.java      | 52 +++++++++++++++++++
 .../ParameterizedJumpSearchTest.java          | 40 ++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 searching/src/main/java/com/wbrawner/algorithms/searching/JumpSearch.java
 create mode 100644 searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedJumpSearchTest.java

diff --git a/README.md b/README.md
index b310512..6de40d4 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,7 @@ Algorithm|Implementation|Tests|Worst Time Complexity|Worst Space Complexity
 -----|-----|-----|:-----:|:-----:
 [Binary Search](https://en.wikipedia.org/wiki/Binary_search_algorithm)|[BinarySearch.java](searching/src/main/java/com/wbrawner/algorithms/searching/BinarySearch.java)|[ParameterizedBinarySearchTest.java](searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedBinarySearchTest.java)|O(log n)|O(1)
 [Fibonacci Search](https://en.wikipedia.org/wiki/Fibonacci_search_technique)|[FibonacciSearch.java](searching/src/main/java/com/wbrawner/algorithms/searching/FibonacciSearch.java)|[ParameterizedFibonacciSearchTest.java](searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedFibonacciSearchTest.java)|O(log n)|O(1)
+[Jump Search](https://en.wikipedia.org/wiki/Jump_search)|[FibonacciSearch.java](searching/src/main/java/com/wbrawner/algorithms/searching/JumpSearch.java)|[ParameterizedJumpSearchTest.java](searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedJumpSearchTest.java)|O(√n)|O(1)
 [Linear Search](https://en.wikipedia.org/wiki/Linear_search)|[LinearSearch.java](searching/src/main/java/com/wbrawner/algorithms/searching/LinearSearch.java)|[ParameterizedLinearSearchTest.java](searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedLinearSearchTest.java)|O(n)|O(1)
 
 ### Sorting
diff --git a/searching/src/main/java/com/wbrawner/algorithms/searching/JumpSearch.java b/searching/src/main/java/com/wbrawner/algorithms/searching/JumpSearch.java
new file mode 100644
index 0000000..dddd2e6
--- /dev/null
+++ b/searching/src/main/java/com/wbrawner/algorithms/searching/JumpSearch.java
@@ -0,0 +1,52 @@
+package com.wbrawner.algorithms.searching;
+
+/**
+ * Jump search requires the array to be sorted, and works by "jumping" through the array by segments that are as long
+ * as the square root of the length of the array until it finds a value greater than the value being searched for, at
+ * which point it returns to the index of the previous value it had and uses the linear search method to find the
+ * given value.
+ */
+class JumpSearch {
+    /**
+     * Search the given array for the given element using the Jump search algorithm
+     *
+     * @return The index of the array where the element can be found or -1 if it can't be found
+     */
+    static int search(int[] array, int element) {
+        if (array.length == 0) {
+            return -1;
+        }
+
+        if (array.length == 1) {
+            return array[0] == element ? 0 : -1;
+        }
+
+        final int jumpSize = (int) Math.sqrt(array.length);
+        int jumpCount = 0;
+        while (true) {
+            int index = jumpSize * jumpCount;
+            if (index >= array.length) {
+                return -1;
+            }
+
+            if (array[index] == element) {
+                return index;
+            }
+
+            if (array[index] < element) {
+                jumpCount++;
+                continue;
+            }
+
+            if (array[index] > element) {
+                for (int i = index - jumpSize; i < index; i++) {
+                    if (array[i] == element) {
+                        return i;
+                    }
+                }
+
+                return -1;
+            }
+        }
+    }
+}
diff --git a/searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedJumpSearchTest.java b/searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedJumpSearchTest.java
new file mode 100644
index 0000000..d043941
--- /dev/null
+++ b/searching/src/test/java/com/wbrawner/algorithms/searching/ParameterizedJumpSearchTest.java
@@ -0,0 +1,40 @@
+package com.wbrawner.algorithms.searching;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import static junit.framework.TestCase.assertEquals;
+import static org.junit.Assume.assumeTrue;
+
+@RunWith(Parameterized.class)
+public class ParameterizedJumpSearchTest {
+
+    @Parameterized.Parameter()
+    public int[] array;
+
+    @Parameterized.Parameter(1)
+    public int searchFor;
+
+    @Parameterized.Parameter(2)
+    public int expectedIndex;
+
+    @Parameterized.Parameter(3)
+    public boolean isSorted;
+
+    @Test
+    public void searchTest() {
+        // The array needs to be sorted for binary search to work.
+        assumeTrue(isSorted);
+
+        assertEquals(
+                expectedIndex,
+                JumpSearch.search(array, searchFor)
+        );
+    }
+
+    @Parameterized.Parameters
+    public static Object[][] getData() {
+        return SearchData.get();
+    }
+}
\ No newline at end of file