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📚 Find the Kth Largest Integer in the Array – Java Cheat Sheet

📌 What Is It?

The Find the Kth Largest Integer in the Array problem involves finding the Kth largest integer in an array of strings, where each string represents an integer. The comparison is based on numerical values.

This problem can be solved using a min-heap to track the top K largest integers.

🧱 Pattern Template

class Solution {
    public String kthLargestNumber(String[] nums, int k) {
        PriorityQueue<String> minHeap = new PriorityQueue<>(
            (a, b) -> {
                if (a.length() == b.length()) {
                    return a.compareTo(b); // Lexicographical comparison
                }
                return Integer.compare(a.length(), b.length()); // Compare by length
            }
        );

        // Step 1: Add elements to the heap
        for (String num : nums) {
            minHeap.offer(num);
            if (minHeap.size() > k) {
                minHeap.poll(); // Remove the smallest element
            }
        }

        // Step 2: The root of the heap is the Kth largest integer
        return minHeap.peek();
    }
}

📊 Time Complexity

• Heap Operations: O(N log K) – Adding and removing elements from the heap.
• Overall Complexity: O(N log K).

✅ Use Cases

• Finding the Kth largest integer in an array of strings
• Efficiently processing large datasets
• Applications in ranking and leaderboard systems

📘 Common LeetCode Problems

• 1985. Find the Kth Largest Integer in the Array [Medium] Heap

🧪 Example: Find the Kth Largest Integer in the Array

Input: nums = ["3","6","7","10"], k = 2
Output: "7"

Explanation:
- The integers are [3, 6, 7, 10].
- The 2nd largest integer is "7".

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💡 Pro Tips

• Use a min-heap to efficiently track the top K largest integers.
• Edge cases: strings with varying lengths, duplicate integers.
• Ensure numerical comparison for strings representing integers.