Merge pull request #559 from Karnak123/1346-Check-if-N-and-its-double-exist

added solution to leetcode problem 1346

Author: vJechsmayr

LeetCode/1346_Check_if_N_and_its_Double_Exist.py

@@ -0,0 +1,9 @@
+class Solution:
+ def checkIfExist(self, arr: List[int]) -> bool:
+
+ seen = set()
+ for x in arr:
+ if x * 2 in seen or (not x % 2 and x // 2 in seen):
+ return True
+ seen.add(x)
+ return False