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
Input: arr = [2,2,3,4] Output: 2 Explanation: The only lucky number in the array is 2 because frequency == 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.
Input: arr = [2,2,2,3,3] Output: -1 Explanation: There are no lucky numbers in the array.
1 <= arr.length <= 500
1 <= arr[i] <= 500
class Solution: def findLucky(self, arr: List[int]) -> int: arr.sort(reverse=True) d = collections.Counter(arr) for k,v in d.items(): if k==v: return k return -1