统计按位或能得到最大值的子集数目

/*
 * Solution approach using Java Streams:
 * 1. Calculate all possible OR values by generating subsets using bitwise operations.
 * 2. Use IntStream to iterate through all subset combinations.
 * 3. Use Collectors.groupingBy to count occurrences of each OR result and find the maximum.
 */
import java.util.*;
import java.util.stream.*;

public class SolutionStream {
    public int countMaxOrSubsets(int[] nums) {
        Map<Integer, Long> orCountMap = IntStream.range(1, 1 << nums.length)
            .map(i -> IntStream.range(0, nums.length)
                .filter(j -> (i & (1 << j)) != 0)
                .map(j -> nums[j])
                .reduce(0, (a, b) -> a | b))
            .boxed()
            .collect(Collectors.groupingBy(orValue -> orValue, Collectors.counting()));

        int maxOr = Collections.max(orCountMap.keySet());
        return orCountMap.get(maxOr).intValue();
    }
}