从零设计关系表：先确定事实，再添加约束

import java.util.*;
public class Main {
    record FD(int left,int right) {}
    static int closure(int bits,int seed,List<FD> rules) {
        if (bits<0||bits>26) throw new IllegalArgumentException("bits");
        int all=(1<<bits)-1;
        if ((seed&~all)!=0) throw new IllegalArgumentException("seed");
        for (FD fd:rules)
            if (((fd.left()|fd.right())&~all)!=0) throw new IllegalArgumentException("rule");
        int known=seed;
        boolean changed;
        do {
            changed=false;
            for (FD fd:rules) {
                // 左部每一位已知，才能推出右部。
                if ((known&fd.left())==fd.left()) {
                    int expanded=known|fd.right();
                    if (expanded!=known) { known=expanded; changed=true; }
                }
            }
            // 只有实际新增属性才继续，循环依赖自然停止。
        } while (changed);
        return known;
    }
    static void eq(int expected,int actual) {
        if (expected!=actual) throw new AssertionError(actual);
    }
    public static void main(String[] args) {
        // A、B、C对应第0、1、2位，规则故意逆序测试多轮推导。
        eq(7,closure(3,1,List.of(new FD(2,4),new FD(1,2))));
        eq(4,closure(3,4,List.of(new FD(1,2),new FD(2,1))));
        eq(3,closure(3,1,List.of(new FD(1,2),new FD(2,1))));
        eq(2,closure(3,0,List.of(new FD(0,2))));
        eq(0,closure(0,0,List.of()));
        try { closure(2,4,List.of()); throw new AssertionError("seed"); }
        catch (IllegalArgumentException expected) {}
        // O、L、P、Q、T、N依次对应订单、行、商品、数量、时间、名称。
        List<FD> detail=List.of(new FD(1,16),new FD(4,32),new FD(3,12));
        eq(63,closure(6,3,detail));
        eq(17,closure(6,1,detail));
        System.out.println("PASS 8 attribute closure tests");
    }
}