我必须在java中编写用于字梯程序的代码。说明如下：
使用递归编写程序以找到给出的字梯 开始单词和结束单词，或确定是否存在单词梯形图。 使用文件“words.txt”作为有效单词的字典。这个 该文件包含87314个单词。你的程序不需要找到 单词之间最短的字梯，任何单词梯都会做到 存在。
例如，从FISH开始，您可以制作一个字梯到MAST 通过以下梯子：
FISH，WISH，WASH，MASH，MAST
以下是words.txt
的链接我觉得我的代码非常接近工作，但我的输出上出现了堆栈溢出错误：
Exception in thread "main" java.lang.StackOverflowError
at java.io.FileOutputStream.write(FileOutputStream.java:326)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
at java.io.PrintStream.write(PrintStream.java:482)
at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
at sun.nio.cs.StreamEncoder.flushBuffer(StreamEncoder.java:104)
at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
我的代码如下：
import java.util.Scanner; import java.io.FileNotFoundException; import java.io.FileInputStream; import java.io.File; import java.io.FileReader; import java.io.PrintWriter; import java.io.FileOutputStream;
public class C11PP8
{
public static void main(String[] args)
{
Scanner inputStream = null;
PrintWriter outputStream = null;
int numWords = 0;
String wordRead = "";
String[] wordLibrary;
String startWord, endWord;
Scanner keyboard = new Scanner(System.in);
int i;
//open for writing four letter words
try
{
outputStream = new PrintWriter(new FileOutputStream("FourLetterWords.txt"));
}//end try
catch(FileNotFoundException e)
{
System.out.println("File not found, program will close.");
System.exit(0);
}//end catch
//open for reading all words
try
{
inputStream = new Scanner(new FileReader("words.txt"));
}//end try
catch(FileNotFoundException e)
{
System.out.println("File not found, program will close.");
System.exit(0);
}//end catch
while(inputStream.hasNextLine())
{
wordRead = inputStream.nextLine();
if(wordRead.length() == 4)
{
wordRead = wordRead.toLowerCase();
outputStream.println(wordRead);
}
}//end while loop
inputStream.close();
outputStream.close();
//open for reading to count number of words
try
{
inputStream = new Scanner(new FileReader("FourLetterWords.txt"));
}//end try
catch(FileNotFoundException e)
{
System.out.println("File not found, program will close.");
System.exit(0);
}//end catch
while(inputStream.hasNextLine())
{
inputStream.nextLine();
++numWords;
}//end while loop
inputStream.close();
//declare
wordLibrary = new String[numWords];
//open FourLetterWord to read
//and populate the array of words
try
{
inputStream = new Scanner(new FileReader("FourLetterWords.txt"));
}//end try
catch(FileNotFoundException e)
{
System.out.println("File not found, program will close.");
System.exit(0);
}//end catch
i = 0;
while(inputStream.hasNextLine())
{
wordLibrary[i] = inputStream.nextLine();
++i;
}//end while loop
inputStream.close();
//confirm
//for(i = 0; i < wordLibrary.length; ++i)
// System.out.println(wordLibrary[i]);
//user input
do
{
System.out.println("Enter your 4 letter start word: ");
startWord = keyboard.nextLine();
}while(startWord.length() != 4);
startWord = startWord.toLowerCase();
do
{
System.out.println("Enter your 4 letter end word: ");
endWord = keyboard.nextLine();
}while(endWord.length() != 4);
endWord = endWord.toLowerCase();
//call the recursive method
findTheWord(startWord, endWord, wordLibrary);
}//end main
public static void findTheWord(String startWordPassed, String endWordPassed, String[] libraryPassed)
{
String currentWord = "";
int count = 0;
//base case
if(endWordPassed.equals(startWordPassed))
{
System.out.println("Word found: " + endWordPassed);
}//end if
else
{
//change a single letter of the startWordPassed and make that the new startWordPassed
// if the new word is in the array
//OR
//iterate through the array and find a word that is only one letter different than startWordPassed
//make that the new startWordPassed
for(int i = 0; i < libraryPassed.length; ++ i)
{
currentWord = libraryPassed[i];
for(int j = 0; j < startWordPassed.length(); ++ j)
{
if(startWordPassed.charAt(j) == currentWord.charAt(j))
++count;
}//end for loop
if( count == 3)
libraryPassed[i] = " ";
}//end for loop
System.out.println(currentWord);
startWordPassed = currentWord;
//recursive call
findTheWord(startWordPassed, endWordPassed, libraryPassed);
}//end else
}//end method
}//end class
我得到的输出是多个“zuni”然后堆栈溢出。 “zuni”是文本文档中最后一个4个字母的单词。
非常感谢任何帮助让它正确运行。
答案 0 :(得分：0)
您的递归方法应返回一些内容，以便程序检测何时需要停止递归。
此外，只有满足条件（count == 3）时才应调用递归方法调用。
将您的findTheWord()方法替换为：
public static boolean findTheWord(String startWordPassed, String endWordPassed, String[] libraryPassed)
{
String currentWord = "";
//base case
if(endWordPassed.equals(startWordPassed))
{
System.out.println("Word found: " + endWordPassed);
return true;
}//end if
else
{
for(int i = 0; i < libraryPassed.length; ++ i)
{
currentWord = libraryPassed[i];
int count = 0;
for(int j = 0; j < startWordPassed.length(); ++ j)
{
if(startWordPassed.charAt(j) == currentWord.charAt(j))
++count;
}//end for loop
if(count == 3) {
libraryPassed[i] = " ";
System.out.println(currentWord);
startWordPassed = currentWord;
//recursive call
if (findTheWord(startWordPassed, endWordPassed, libraryPassed)) {
return true;
}
}
}//end for loop
}//end else
return false;
}//end method
为了覆盖没有梯子的情况，你可以在main方法中使用findTheWord()的返回值：
public static void main(String[] args) {
...
...
//call the recursive method
if (!findTheWord(startWord, endWord, wordLibrary)) {
System.out.println("No ladder exists");
}
}
答案 1 :(得分：-1)
将此方法用于＆＃34; findTheWord＆＃34;你会得到你想要的结果
public static void findTheWord(String startWordPassed,
String endWordPassed, String[] libraryPassed) {
String currentWord = "";
int count = 0;
// base case
if (endWordPassed.equals(startWordPassed)) {
System.out.println("Word found: " + endWordPassed);
}// end if
else {
// change a single letter of the startWordPassed and make that the
// new startWordPassed
// if the new word is in the array
// OR
Map<String, Integer> index = new HashMap<String, Integer>();
for (int i = 0; i < libraryPassed.length; i++) {
index.put(libraryPassed[i], i);
}
System.out.println("Start Index:" + index.get(startWordPassed));
System.out.println("End Index:" + index.get(endWordPassed));
// iterate through the array and find a word that is only one letter
// different than startWordPassed
// make that the new startWordPassed
System.out.println("Start Word:" + startWordPassed);
int startIndex = index.get(startWordPassed) + 1;
int endIndex = index.get(endWordPassed);
for (int i = startIndex; i < endIndex; i++) {
currentWord = libraryPassed[i];
//System.out.println("current word:"+currentWord);
count = 0;
for (int j = 0; j < startWordPassed.length(); ++j) {
if (startWordPassed.charAt(j) == currentWord.charAt(j))
++count;
}// end for loop
if (count == 3)
{
startWordPassed = currentWord;
System.out.println("Ladder Word:"+startWordPassed);
}
}// end for loop
}// end else
}// end method