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
class Solution {
public int findLucky(int[] arr) {
HashMap<Integer,Integer> hm = new HashMap<>();
for(int i=0;i<arr.length;i++){
int ele = arr[i];
if(hm.containsKey(ele)==true){
hm.put(ele,hm.get(ele)+1);
}else{
hm.put(ele,1);
}
}
int ans = -1 ;
for(int key : hm.keySet()){
if(hm.get(key)==key){
ans = Math.max(ans,key);
}
}
return ans ;
}
}
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