笨阶乘

// Java Stream solution for the problem
// The solution requires using Java Streams to apply the sequence of operations: *, /, +, - in a loop.
// We use a List to hold the elements and then apply reduce to combine them.

import java.util.stream.IntStream;

public class ClumsyFactorialStream {
    public int clumsy(int N) {
        return IntStream.rangeClosed(1, N)
                .map(i -> N - i + 1)
                .boxed()
                .reduce(new int[]{0, 1}, (acc, n) -> {
                    int op = (N - n) % 4;
                    if (op == 0) {
                        acc[1] *= n; // Multiplication
                    } else if (op == 1) {
                        acc[1] /= n; // Floor Division
                    } else if (op == 2) {
                        acc[0] += acc[1]; // Addition
                        acc[1] = n; // Prepare for subtraction
                    } else {
                        acc[0] -= acc[1]; // Subtraction
                        acc[1] = n; // Prepare for next multiplication
                    }
                    return acc;
                }, (a, b) -> a)[0];
    }
}