JAVA编程算法50例.doc

写一个函数，例如：给你的 a b c 则输出 abc acb bac bca cab cba import?java.util.ArrayList; ?? import?java.util.List; ?? ??public?class?NumTest?{ ?? ??????public?static?void?main(String[]?args)?{ ?? ????????String?s=ABCD;//原字符串 ?? ????????ListString?result?=?list(s,?);//列出字符的组合，放入result ?? ????????System.out.println(result.size());; ?? ????????System.out.println(result); ?? ????} ?? ????/** ? ?????*?列出基础字符串(base)的所有组合 ? ?????*?@param?base?以该字符串作为基础字符串，进行选择性组合。 ? ?????*?@param?buff?所求字符串的临时结果 ? ?????*?@param?result?存放所求结果 ? ?????*/?? ????public?static?ListString?list(String?base,String?buff){ ?? ????????ListString?result?=?new?ArrayListString();//存放结果信息。 ?? ????????if(base.length()=0){ ?? ????????????result.add(buff); ?? ????????} ?? ????????for(int?i=0;ibase.length();i++){ ?? ????????????ListString?temp?=?list(new?StringBuilder(base).deleteCharAt(i).toString(),buff+base.charAt(i)); ?? ????????????result.addAll(temp); ?? ???????????? ?? ????????} ?? ????????return?result; ?? ????} ?? } +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ public?static?void?main(String[]?args)?{ ?? ????String?s=ABCD;//原字符串 ?? ????ListString?result?=?new?ArrayListString();//存放结果信息。 ?? ????list(s,?,?result);//列出字符的组合，放入result ?? ????System.out.println(result.size());; ?? ????System.out.println(result); ?? } ?? ?? /** ? ?*?列出基础字符串(base)的所有组合 ? ?*?@param?base?以该字符串作为基础字符串，进行选择性组合。 ? ?*?@param?buff?所求字符串的临时结果 ? ?*?@param?result?存放所求结果 ? ?*/?? public?static?void?list(String?base,String?buff,ListString?result){ ?? ????if(base.length()=0){ ?? ????????result.add(buff); ?? ????} ?? ????for(int?i=0;ibase.length();i++){ ?? ????????list(new?StringBuilder(base).deleteCharAt(i).toString(),buff+base.charAt(i),result); ?? ????} ?? }? +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 写一个函数，给你一个字符串 倒序输出来 public String getString(String str){ if(str!=null){ String newStr = ; for(int i=0;istr.length();i++) { char c = str.charAt(str.length()-1-i); newStr = newStr +