LeetCode-in-Java
1394. Find Lucky Integer in an Array
Easy
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 <= 5001 <= arr[i] <= 500
Solution
public class Solution {
public int findLucky(int[] arr) {
int[] numbers = new int[501];
for (int j : arr) {
numbers[j]++;
}
for (int i = 500; i > 0; i--) {
if (i == numbers[i]) {
return i;
}
}
return -1;
}
}