最长半递减数组

/*
 * LeetCode 2863: Longest Semi-Decreasing Subarray using Java Streams
 * 
 * Problem Statement:
 * Given an array of integers, find the length of the longest semi-decreasing subarray. 
 * A semi-decreasing subarray is one where for any two consecutive elements a[i] and a[i+1], a[i] >= a[i+1].
 * 
 * Approach:
 * 1. Convert the array to a list of indexes.
 * 2. Use stream operations to find the longest semi-decreasing subarray.
 * 3. Iterate through the list with a reduction operation to keep track of the longest subarray length.
 */
import java.util.*;
import java.util.stream.*;

public class Solution {
    public int longestSemiDecreasingSubarray(int[] nums) {
        if (nums.length == 0) return 0;
        return IntStream.range(0, nums.length - 1)
                .mapToObj(i -> nums[i] >= nums[i + 1] ? 1 : 0)
                .collect(ArrayList::new, (list, val) -> {
                    if (val == 1) {
                        if (!list.isEmpty() && list.get(list.size() - 1) > 0) {
                            list.set(list.size() - 1, list.get(list.size() - 1) + 1);
                        } else {
                            list.add(1);
                        }
                    } else {
                        list.add(0);
                    }
                }, ArrayList::addAll)
                .stream()
                .max(Integer::compare)
                .orElse(1);
    }
}