分割数组为连续子序列

/*
 * 题目思路：
 * 1. 使用 Java Stream 对输入数组进行处理。
 * 2. 统计每个数字的出现次数。
 * 3. 使用 Stream API 的特性来处理子序列的添加和创建。
 */
 
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
 
public class SplitArrayIntoSubsequencesStream {
    public boolean isPossible(int[] nums) {
        Map<Integer, Long> freq = IntStream.of(nums).boxed()
                .collect(Collectors.groupingBy(n -> n, Collectors.counting()));
        Map<Integer, Long> appendFreq = new HashMap<>();
 
        for (int num : nums) {
            if (freq.get(num) == 0) continue;
 
            if (appendFreq.getOrDefault(num, 0L) > 0) {
                appendFreq.put(num, appendFreq.get(num) - 1);
                appendFreq.put(num + 1, appendFreq.getOrDefault(num + 1, 0L) + 1);
            } else if (freq.getOrDefault(num + 1, 0L) > 0 && freq.getOrDefault(num + 2, 0L) > 0) {
                freq.put(num + 1, freq.get(num + 1) - 1);
                freq.put(num + 2, freq.get(num + 2) - 1);
                appendFreq.put(num + 3, appendFreq.getOrDefault(num + 3, 0L) + 1);
            } else {
                return false;
            }
 
            freq.put(num, freq.get(num) - 1);
        }
 
        return true;
    }
}