Day 39.2.txt

1394. Find Lucky Integer in an Array

Given an array of integers arr, a lucky integer is an integer which has a frequency in the array equal to its value.

Return a lucky integer in the array. If there are multiple lucky integers return the largest of them. 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.
Example 4:

Input: arr = [5]
Output: -1
Example 5:

Input: arr = [7,7,7,7,7,7,7]
Output: 7
 

Constraints:

1 <= arr.length <= 500
1 <= arr[i] <= 500


class Solution {
    public int findLucky(int[] a) {
        HashMap<Integer,Integer> nm=new HashMap<>();
        int i,c=-1;
        for(i=0;i<a.length;i++)
        {
            if(nm.containsKey(a[i]))
                nm.put(a[i] , nm.get(a[i])+1);
            else
                nm.put(a[i],1);
        }
        for(int k : nm.keySet())
        {
            if(k==nm.get(k))
                c=k;
        }
        return c;
    }
}