计算JSON驱动的问卷调查的可能路径数：Java递归实现-java教程-PHP中文网

计算JSON驱动的问卷调查的可能路径数：Java递归实现

心靈之曲

发布： 2025-08-22 21:16:01

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计算json驱动的问卷调查的可能路径数：java递归实现

本文旨在提供一种使用Java和递归算法，计算基于JSON配置的问卷调查中所有可能的路径数量的解决方案。我们将深入探讨如何解析JSON结构，并使用递归函数遍历所有可能的答案分支，最终计算出完成问卷调查的不同方式的总数。此外，还将讨论在设计此类问卷调查逻辑时的一些注意事项。

理解JSON问卷结构

首先，我们需要理解JSON问卷的结构。在提供的例子中，JSON对象的键表示问题，而键对应的值又是一个JSON对象，该对象的键表示问题的答案，值则表示下一个问题。如果值为以"0 "开头的字符串，则表示问卷结束。

{
  "What is your marital status?": {
    "Single": "Are you planning on getting married next year?",
    "Married": "How long have you been married?"
  },
  "Are you planning on getting married next year?": {
    "Yes": "0 Thanks for your answers! We hope that you will build a cool family!",
    "No": "0 Thanks for your answers! Who knows, maybe you'll find someone significant in your life!"
  },
  "How long have you been married?": {
    "Less than a year": "0 Thanks for your answers! We hope that you will celebrate your one year anniversary soon!",
    "More than a year": "Have you celebrated your one year anniversary?"
  },
  "Have you celebrated your one year anniversary?": {
    "Yes": "0 Wow, cool! Keep it up! Thanks for your answers.",
    "No": "0 We think you should fix it next time! Thanks for your answers!"
  }
}

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递归计算路径数

为了计算所有可能的路径，我们可以使用递归函数。该函数接受JSON节点和当前问题作为参数。

基本情况: 如果当前问题没有对应的答案（即，到达问卷的末尾），则返回1，表示找到了一条有效路径。
递归步骤: 如果当前问题有对应的答案，则遍历所有可能的答案。对于每个答案，递归调用该函数，并将下一个问题作为参数传递。将所有递归调用的结果相加，得到总的路径数。

以下是Java代码示例，使用了Jackson库来解析JSON：

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import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.util.concurrent.atomic.AtomicInteger;

public class QuizService {

    public static int countWays(JsonNode node, String question) {
        JsonNode answers = node.get(question);
        if (answers == null) {
            return 1;
        }
        AtomicInteger ways = new AtomicInteger();
        answers.fields().forEachRemaining(answer ->
                ways.addAndGet(countWays(node, answer.getValue().asText())));
        return ways.get();
    }

    public static void main(String[] args) throws IOException {
        String jsonString = "{" +
                "  \"What is your marital status?\": {" +
                "    \"Single\": \"Are you planning on getting married next year?\"," +
                "    \"Married\": \"How long have you been married?\"" +
                "  }," +
                "  \"Are you planning on getting married next year?\": {" +
                "    \"Yes\": \"0 Thanks for your answers! We hope that you will build a cool family!\"," +
                "    \"No\": \"0 Thanks for your answers! Who knows, maybe you'll find someone significant in your life!\"" +
                "  }," +
                "  \"How long have you been married?\": {" +
                "    \"Less than a year\": \"0 Thanks for your answers! We hope that you will celebrate your one year anniversary soon!\"," +
                "    \"More than a year\": \"Have you celebrated your one year anniversary?\"" +
                "  }," +
                "  \"Have you celebrated your one year anniversary?\": {" +
                "    \"Yes\": \"0 Wow, cool! Keep it up! Thanks for your answers.\"," +
                "    \"No\": \"0 We think you should fix it next time! Thanks for your answers!\"" +
                "  }" +
                "}";

        ObjectMapper mapper = new ObjectMapper();
        JsonNode node = mapper.readTree(jsonString);
        System.out.println(countWays(node, "What is your marital status?")); // Output: 4
    }
}

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代码解释:

countWays(JsonNode node, String question): 递归函数，用于计算从给定问题开始的路径数。
JsonNode answers = node.get(question);: 获取当前问题的所有答案。
if (answers == null): 如果当前问题没有答案，说明到达了问卷的终点，返回1。
answers.fields().forEachRemaining(answer -> ...): 遍历所有可能的答案。
ways.addAndGet(countWays(node, answer.getValue().asText())): 递归调用 countWays 函数，并将下一个问题作为参数传递。
ObjectMapper mapper = new ObjectMapper();: 创建 Jackson ObjectMapper 对象，用于解析 JSON 字符串。
JsonNode node = mapper.readTree(jsonString);: 将 JSON 字符串解析为 JsonNode 对象。