contains-duplicate solution

Author: shinheekim

.gitignore

@@ -2,3 +2,4 @@
 .vscode/
 .DS_Store
 .env
+/leetcode-study.iml

contains-duplicate/shinheekim.java

@@ -0,0 +1,15 @@
+import java.util.HashSet;
+import java.util.Set;
+
+class Solution {
+    public boolean containsDuplicate(int[] nums) {
+        Set<Integer> visited = new HashSet<>();
+
+        for (int n : nums){
+            if (!visited.add(n)){
+                return true;
+            }
+        }
+        return false; // 모든 값이 고유할 때
+    }
+}