content: package codingquestions.leetcode;
  
  /*
  1394. Find Lucky Integer in an Array
  Solved
  Easy
  Topics
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  Hint
  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
  */
  public class FindLuckyIntegerInAnArray {
      public int findLucky(int[] arr) {
          int[] frequency = new int[502];
          for (int i : arr)
              frequency[i]++;
  
          for (int i = frequency.length - 1; i >= 1; i--) {
              if (i == frequency[i])
                  return i;
          }
          return -1;
      }
  }
  