数据结构性学习递归实现字母串全排列等

最新推荐文章于 2022-11-22 20:31:11 发布

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本文介绍了一种使用Java编程语言实现单词乱序生成的方法，通过分治算法和递归技巧，实现对输入字符串的字母重新排列，生成一系列乱序后的同义词组合。

// anagram.java
// creates anagrams
// to run this program: C>java AnagramApp
import java.io.*;
////////////////////////////////////////////////////////////////
class AnagramApp
   {
   static int size;
   static int count;
   static char[] arrChar = new char[100];
   //-----------------------------------------------------------
   public static void main(String[] args) throws IOException
      {
      System.out.print("Enter a word: ");    // get word
      String input = getString();
      size = input.length();                 // find its size
      count = 0;
      for(int j=0; j<size; j++)              // put it in array
         arrChar[j] = input.charAt(j);
      doAnagram(size);                       // anagram it
      }  // end main()
   //-----------------------------------------------------------
   public static void doAnagram(int newSize)
      {
      int limit;
      if(newSize == 1)                     // if too small,
         return;                           // go no further

      for(int j=0; j<newSize; j++)         // for each position,
         {
         doAnagram(newSize-1);             // anagram remaining
         if(newSize==2)                    // if innermost,
            displayWord();                 // display it
         rotate(newSize);                  // rotate word
         }
      }
   //-----------------------------------------------------------
   // rotate left all chars from position to end
   public static void rotate(int newSize)
      {
      int j;
      int position = size - newSize;
      char temp = arrChar[position];       // save first letter
      for(j=position+1; j<size; j++)       // shift others left
         arrChar[j-1] = arrChar[j];
      arrChar[j-1] = temp;                 // put first on right
      }
   //-----------------------------------------------------------
   public static void displayWord()
      {
      if(count < 99)
         System.out.print(" ");
      if(count < 9)
         System.out.print(" ");
      System.out.print(++count + " ");
      for(int j=0; j<size; j++)
         System.out.print( arrChar[j] );
      System.out.print("   ");
      System.out.flush();
      if(count%6 == 0)
         System.out.println("");
      }
   //-----------------------------------------------------------
   public static String getString() throws IOException
      {
      InputStreamReader isr = new InputStreamReader(System.in);
      BufferedReader br = new BufferedReader(isr);
      String s = br.readLine();
      return s;
      }
   //-----------------------------------------------------------
   }  // end class AnagramApp
////////////////////////////////////////////////////////////////

分治算法