LeetBook--哈希表--存在重复元素

src/main/java/leet/book/hashTablePlus/ContainsDuplicate.java

@@ -0,0 +1,20 @@
+package leet.book.hashTablePlus;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class ContainsDuplicate {
+
+    class Solution {
+        public boolean containsDuplicate(int[] nums) {
+            Set<Integer> set = new HashSet<>();
+            for (int num : nums) {
+                if (set.contains(num)) {
+                    return false;
+                }
+                set.add(num);
+            }
+            return true;
+        }
+    }
+}

src/main/java/leet/book/queueStack/UpdateMatrix.java

@@ -1,8 +1,6 @@
 package leet.book.queueStack;
 
-import java.util.Arrays;
 import java.util.LinkedList;
-import java.util.List;
 import java.util.Queue;
 
 /**