计算JSON驱动的问卷调查的可能路径数：Java递归实现-小浪学习网

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!"   } }

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     } }

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。