From 528e19f9a9c59e928644c832b0adf09cd77e14de Mon Sep 17 00:00:00 2001
From: nguyensonphong <61722969+nguyensonphong@users.noreply.github.com>
Date: Fri, 3 Jul 2020 09:48:03 +0800
Subject: [PATCH] Update countCommon.java

use Set Operations.
---
 chapter-11/countCommon.java | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/chapter-11/countCommon.java b/chapter-11/countCommon.java
index 2aae1e4..8bde43d 100644
--- a/chapter-11/countCommon.java
+++ b/chapter-11/countCommon.java
@@ -5,6 +5,7 @@
 */
 
 public static int countCommon(List<Integer> list1, List<Integer> list2) {
+    /*
     Set<Integer> set = new HashSet<Integer>(list1);
     Iterator<Integer> i = set.iterator();
     int count = 0;
@@ -16,4 +17,10 @@ public static int countCommon(List<Integer> list1, List<Integer> list2) {
     }
     
     return count;
+    */
+    Set<Integer> s1 = new HashSet<>(list1);
+    Set<Integer> s2 = new HashSet<>(list2);
+    s1.retainAll(s2);
+    
+    return s1;
 }