From 5043f89df6132ccf106dab6f212ed8999b03bc09 Mon Sep 17 00:00:00 2001
From: shellhub <shellhub.me@gmail.com>
Date: Sat, 28 Sep 2019 16:26:10 +0800
Subject: [PATCH] Find max and min value by recursion

---
 Maths/FindMaxRecursion.java | 32 ++++++++++++++++++++++++++++++++
 Maths/FindMinRecursion.java | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 Maths/FindMaxRecursion.java
 create mode 100644 Maths/FindMinRecursion.java

diff --git a/Maths/FindMaxRecursion.java b/Maths/FindMaxRecursion.java
new file mode 100644
index 00000000..3ebcaf39
--- /dev/null
+++ b/Maths/FindMaxRecursion.java
@@ -0,0 +1,32 @@
+package Maths;
+
+public class FindMaxRecursion {
+    public static void main(String[] args) {
+        int[] array = {2, 4, 9, 7, 19, 94, 5};
+        int low = 0;
+        int high = array.length - 1;
+
+        System.out.println("max value is " + max(array, low, high));
+    }
+
+    /**
+     * Get max of array using divide and conquer algorithm
+     *
+     * @param array contains elements
+     * @param low   the index of the first element
+     * @param high  the index of the last element
+     * @return max of {@code array}
+     */
+    public static int max(int[] array, int low, int high) {
+        if (low == high) {
+            return array[low]; //or array[high]
+        }
+
+        int mid = (low + high) >>> 1;
+
+        int leftMax = max(array, low, mid); //get max in [low, mid]
+        int rightMax = max(array, mid + 1, high); //get max in [mid+1, high]
+
+        return leftMax >= rightMax ? leftMax : rightMax;
+    }
+}
diff --git a/Maths/FindMinRecursion.java b/Maths/FindMinRecursion.java
new file mode 100644
index 00000000..292ffc30
--- /dev/null
+++ b/Maths/FindMinRecursion.java
@@ -0,0 +1,32 @@
+package Maths;
+
+public class FindMinRecursion {
+    public static void main(String[] args) {
+        int[] array = {2, 4, 9, 7, 19, 94, 5};
+        int low = 0;
+        int high = array.length - 1;
+
+        System.out.println("min value is " + min(array, low, high));
+    }
+
+    /**
+     * Get min of array using divide and conquer algorithm
+     *
+     * @param array contains elements
+     * @param low   the index of the first element
+     * @param high  the index of the last element
+     * @return min of {@code array}
+     */
+    public static int min(int[] array, int low, int high) {
+        if (low == high) {
+            return array[low]; //or array[high]
+        }
+
+        int mid = (low + high) >>> 1;
+
+        int leftMin = min(array, low, mid); //get min in [low, mid]
+        int rightMin = min(array, mid + 1, high); //get min in [mid+1, high]
+
+        return leftMin <= rightMin ? leftMin : rightMin;
+    }
+}