吃掉 N 个橘子的最少天数

// Solution using Java Streams
// Java Streams are not particularly suited for this problem as it involves state changes and is naturally iterative. However, we can use them to represent the basic operations. Here we present a combination of functional style with traditional iteration.

import java.util.HashSet;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Set;

public class SolutionStream {
    public int minDays(int n) {
        Queue<int[]> queue = new LinkedList<>();
        Set<Integer> visited = new HashSet<>();
        queue.add(new int[]{n, 0});
        visited.add(n);
        while (!queue.isEmpty()) {
            int[] current = queue.poll();
            int oranges = current[0];
            int days = current[1];
            if (oranges == 0) {
                return days;
            }
            if (visited.add(oranges - 1)) {
                queue.add(new int[]{oranges - 1, days + 1});
            }
            if (oranges % 2 == 0 && visited.add(oranges / 2)) {
                queue.add(new int[]{oranges / 2, days + 1});
            }
            if (oranges % 3 == 0 && visited.add(oranges - (2 * (oranges / 3)))) {
                queue.add(new int[]{oranges - (2 * (oranges / 3)), days + 1});
            }
        }
        return -1;
    }
}