From 45758ee4388d27fdfe93ae33122029cc80278093 Mon Sep 17 00:00:00 2001
From: Ivan Li <email2liyang@gmail.com>
Date: Tue, 29 Jan 2019 17:22:19 +0800
Subject: [PATCH] bag weight

---
 .../scala/ch39_back_tracking/BagWeight.scala  | 25 +++++++++++++++++++
 .../ch39_back_tracking/BagWeightTest.scala    | 15 +++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 scala/src/main/scala/ch39_back_tracking/BagWeight.scala
 create mode 100644 scala/src/test/scala/ch39_back_tracking/BagWeightTest.scala

diff --git a/scala/src/main/scala/ch39_back_tracking/BagWeight.scala b/scala/src/main/scala/ch39_back_tracking/BagWeight.scala
new file mode 100644
index 0000000..bfc5c21
--- /dev/null
+++ b/scala/src/main/scala/ch39_back_tracking/BagWeight.scala
@@ -0,0 +1,25 @@
+package ch39_back_tracking
+
+class BagWeight(maxBagItemCount: Int, maxBagWeight: Int) {
+
+  def calculateMaxWeight(items: Array[Int]): Int = {
+    var maxWeight = 0
+
+    def _calcMaxWeight(itemIndex: Int, currentWeight: Int): Unit = {
+      if (currentWeight == maxBagWeight || itemIndex == items.length) {
+        if (currentWeight > maxWeight) {
+          maxWeight = currentWeight
+        }
+      } else {
+        //check next item
+        _calcMaxWeight(itemIndex + 1, currentWeight)
+        if (currentWeight + items(itemIndex) <= maxBagWeight) {
+          _calcMaxWeight(itemIndex + 1, currentWeight + items(itemIndex))
+        }
+      }
+    }
+
+    _calcMaxWeight(0, 0)
+    maxWeight
+  }
+}
diff --git a/scala/src/test/scala/ch39_back_tracking/BagWeightTest.scala b/scala/src/test/scala/ch39_back_tracking/BagWeightTest.scala
new file mode 100644
index 0000000..870754b
--- /dev/null
+++ b/scala/src/test/scala/ch39_back_tracking/BagWeightTest.scala
@@ -0,0 +1,15 @@
+package ch39_back_tracking
+
+import org.scalatest.FlatSpec
+
+class BagWeightTest extends FlatSpec {
+
+  behavior of "BagWeightTest"
+
+  it should "calculateMaxWeight" in {
+    val bagWeight = new BagWeight(5,9)
+    val maxWeight = bagWeight.calculateMaxWeight(Array(1,2,3,5,6))
+    println(maxWeight)
+  }
+
+}