Question

无法弄清楚如何将此递归方法更改为迭代方法，任何人都有任何有用的指针？我得到了递归方法的工作原理，但不太确定转换为迭代的步骤，谢谢。

private static void printFriends(Friend friend, int distance) {
        if (distance == 0) {
            System.out.println(friend);
        } else {
            for (Friend f : friend.getFriends()) {
                System.out.println(f + "0");
                printFriends(f, distance - 1);
            }
        }
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        List<Friend> friendList = new ArrayList<Friend>();

        Friend reuben = new Friend("Reuben");
        Friend soumitra = new Friend("Soumitra");
        Friend ken = new Friend("Ken");
        Friend elisa = new Friend("Elisa");
        Friend isaac = new Friend("Isaac");

        friendList.add(reuben);
        friendList.add(soumitra);
        friendList.add(ken);
        friendList.add(elisa);
        friendList.add(isaac);

        reuben.addFriend(soumitra);
        reuben.addFriend(ken);

        soumitra.addFriend(reuben);

        ken.addFriend(reuben);
        ken.addFriend(elisa);

        elisa.addFriend(ken);
        elisa.addFriend(isaac);

        isaac.addFriend(elisa);

        BufferedReader inputReader = new BufferedReader(new InputStreamReader(System.in));
        String inputName = "";
        String inputValue = "";
        Friend inputFriend = null;
        int inputInt = 0;

        System.out.println("Blank entry at any prompt exits program.");

        while (true) {
            System.out.print("Enter a person's name: ");
            try {
                inputName = inputReader.readLine();
            } catch (IOException e) {
                System.err.println("Error reading from console.");
            }

            if (inputName.equals("")) {
                System.out.println("Run complete.");
                System.exit(0);
            }

            inputFriend = new Friend(inputName);

            if (friendList.contains(inputFriend)) {
                inputFriend = friendList.get(friendList.indexOf(inputFriend));
                System.out.print("Enter a non-negative integer: ");
                try {
                    inputValue = inputReader.readLine();
                } catch (IOException e) {
                    System.err.println("Error reading from console.");
                }

                if (inputValue.equals("")) {
                    System.out.println("Run complete.");
                    System.exit(0);
                }

                try {
                    inputInt = Integer.valueOf(inputValue);
                } catch (NumberFormatException e) {
                    System.err.println("Must enter integer.");
                    continue;
                }

                if (inputInt < 0) {
                    System.out.println("Must be non-negative");
                } else {
                    printFriends(inputFriend, inputInt);
                }
            } else {
                System.out.println(inputFriend + " not found.");
            }
        }
    }
}

Answer 1

查看您的代码，您似乎正在使用距离＆＃39;参数作为要打印的朋友数的计数器，因此是递归调用该方法的次数。您可以使用for循环或while循环结构轻松转换它，并使用distance参数作为循环的终止条件。我建议使用for循环，因为它有助于简化代码。

For loop construct：https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html

for (int i = 0; i < distance; i++) {
//list.get(i);
//printfriends + "0"
}

确保熟悉java中的所有基本循环结构。

将递归循环更改为迭代

1 个答案: