Find Lucky Integer in an Array
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
2The only lucky number in the array is 2 because frequency[2] == 2.
Example 2
Input
arr = [1,2,2,3,3,3]Output
31, 2 and 3 are all lucky numbers, so return the largest of them.
Constraints
- 1 <= arr.length <= 500
- 1 <= arr[i] <= 500