Given an array of integers arr
, a lucky integer is an integer that has a frequency in the array equal to its value.
Return the largest lucky integer in the array. If there is no lucky integer return -1
.
Example 1:
Input: arr = [2,2,3,4]
Output: 2
Explanation: The only lucky number in the array is 2 because frequency[2] == 2.
Example 2:
Input: arr = [1,2,2,3,3,3]
Output: 3
Explanation: 1, 2 and 3 are all lucky numbers, return the largest of them.
Example 3:
Input: arr = [2,2,2,3,3]
Output: -1
Explanation: There are no lucky numbers in the array.
Constraints:
-
1 <= arr.length <= 500
-
1 <= arr[i] <= 500
SOLUTION:
from collections import Counter
class Solution:
def findLucky(self, arr: List[int]) -> int:
ctr = Counter(arr)
return max([k for k, v in ctr.items() if k == v] + [-1])
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