LeetCode 1394: Find Lucky Integer in an Array Solution
Master LeetCode problem 1394 (Find Lucky Integer in an Array), a easy challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.
1394. Find Lucky Integer in an Array
Problem Explanation
Explanation
To solve this problem, we can iterate through the array and count the frequency of each integer using a HashMap. Then, we can iterate through the HashMap to find the largest lucky integer where the frequency equals the integer value. If no lucky integer is found, we return -1.
- Time complexity: O(n) where n is the number of elements in the array.
- Space complexity: O(n) to store the frequencies in the HashMap.
Solution Code
import java.util.HashMap;
class Solution {
public int findLucky(int[] arr) {
HashMap<Integer, Integer> freqMap = new HashMap<>();
for (int num : arr) {
freqMap.put(num, freqMap.getOrDefault(num, 0) + 1);
}
int maxLucky = -1;
for (int key : freqMap.keySet()) {
if (freqMap.get(key) == key) {
maxLucky = Math.max(maxLucky, key);
}
}
return maxLucky;
}
}Try It Yourself
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