add solution of contains-duplicate

Author: jinhyungrhee

contains-duplicate/jinhyungrhee.java

@@ -0,0 +1,16 @@
+import java.util.*;
+class Solution {
+    public boolean containsDuplicate(int[] nums) {
+        /**
+         avg : O(NlogN)
+         worst : O(N^2)
+         */
+        Arrays.sort(nums);
+
+        for (int i = 1; i < nums.length; i++) {
+            if (nums[i-1] == nums[i]) return true;
+        }
+
+        return false;
+    }
+}