# Lucky integer in an array leetcode solution.

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

```
class Solution {
public int findLucky(int[] arr) {
int[] count = new int[501];
for (int i = 0; i < arr.length; i++) {
count[arr[i]]++;
}
int max = -1;
for (int i = 1; i < count.length; i++) {
if (count[i] == i) {
max = Math.max(max, i);
}
}
return max;
}
}
```