added task #1346 solution

Author: nesterrovv

src/task_1346/Solution.java

@@ -0,0 +1,21 @@
+package task_1346;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class Solution {
+    public boolean checkIfExist(int[] arr) {
+        Set<Integer> set = new HashSet<>();
+        for (int i = 0; i < arr.length; i++) {
+            if (set.contains(arr[i] * 2)) {
+                return true;
+            }
+            if (arr[i] % 2 == 0 && set.contains(arr[i] / 2)) {
+                return true;
+            }
+            set.add(arr[i]);
+        }
+        return false;
+    }
+
+}