统计 K-Big 索引的数量

/*
 * 2519. Count the Number of K-Big Indices using Java Streams
 * 
 * Problem Statement:
 * Given an array of integers nums and an integer k, we call an index i K-Big if 
 * there are at least k elements in nums that are greater than nums[i].
 * Return the number of K-Big indices.
 * 
 * Example:
 * Input: nums = [3, 2, 3, 4, 6], k = 2
 * Output: 3
 * Explanation: The K-Big indices are 0, 2, and 3 because there are at least 2 elements in the array that are greater than nums[0], nums[2], and nums[3].
 */

import java.util.Arrays;
import java.util.stream.IntStream;

public class CountKBigIndicesStream {
    public static long countKBigIndices(int[] nums, int k) {
        // Step 1: Sort the array
        int[] sorted = nums.clone();
        Arrays.sort(sorted);

        // Step 2: Use streams to count K-Big indices
        return IntStream.of(nums)
                .filter(num -> sorted.length - Arrays.binarySearch(sorted, num) - 1 >= k)
                .count();
    }

    public static void main(String[] args) {
        int[] nums = {3, 2, 3, 4, 6};
        int k = 2;
        System.out.println(countKBigIndices(nums, k)); // Output: 3
    }
}