Given an array arr
of integers, check if there exists two integers N
and M
such that N
is the double of M
( i.e. N = 2 * M
).
More formally check if there exists two indices i
and j
such that :
-
i != j
-
0 <= i, j < arr.length
-
arr[i] == 2 * arr[j]
Example 1:
Input: arr = [10,2,5,3]
Output: true
Explanation: N = 10
is the double of M = 5
,that is, 10 = 2 * 5
.
Example 2:
Input: arr = [7,1,14,11]
Output: true
Explanation: N = 14
is the double of M = 7
,that is, 14 = 2 * 7
.
Example 3:
Input: arr = [3,1,7,11]
Output: false
Explanation: In this case does not exist N and M, such that N = 2 * M.
Constraints:
-
2 <= arr.length <= 500
-
-10^3 <= arr[i] <= 10^3
SOLUTION:
class Solution:
def checkIfExist(self, arr: List[int]) -> bool:
arr.sort(reverse = True, key = lambda x: abs(x))
exists = set()
for num in arr:
if num * 2 in exists:
return True
exists.add(num)
return False
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