股票平滑下跌阶段的数目

/*
 * 思路：
 * 1. 使用 Java Stream 解决该问题需要先将原始数组转换成包含前后元素比较结果的布尔数组。
 * 2. 然后通过 reduce 操作累计平滑下降阶段的长度和计数。
 */
import java.util.stream.IntStream;

public class SmoothDescendingStagesStream {
    public int countSmoothDescendingStages(int[] prices) {
        int[] descLengths = new int[prices.length];
        descLengths[0] = 1;
        IntStream.range(1, prices.length).forEach(i -> {
            descLengths[i] = (prices[i] == prices[i - 1] - 1) ? descLengths[i - 1] + 1 : 1;
        });
        return IntStream.of(descLengths).sum();
    }

    public static void main(String[] args) {
        SmoothDescendingStagesStream sds = new SmoothDescendingStagesStream();
        int[] prices = {3, 2, 1, 4};
        System.out.println(sds.countSmoothDescendingStages(prices)); // 输出 7
    }
}