下一个数

/*
 * 思路：
 * 1. 使用Java Stream进行优化，通过IntStream查找满足条件的数。
 */

import java.util.stream.IntStream;

public class NextNumberStream {
    public static int[] findNextNumbers(int num) {
        int countOnes = Integer.bitCount(num);
        int larger = IntStream.iterate(num + 1, i -> i + 1)
                              .filter(i -> Integer.bitCount(i) == countOnes)
                              .findFirst()
                              .orElse(-1);

        int smaller = IntStream.iterate(num - 1, i -> i - 1)
                               .filter(i -> Integer.bitCount(i) == countOnes)
                               .filter(i -> i > 0)
                               .findFirst()
                               .orElse(-1);

        return new int[]{larger, smaller};
    }

    public static void main(String[] args) {
        int num = 2;
        int[] result = findNextNumbers(num);
        System.out.println("[" + result[0] + ", " + result[1] + "]");
    }
}