从文件读取字符串，并求出该字符串包含的字符集中所有字符的全部组合

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求给定字符集中所有字符的全部组合。首先从文件“data.txt”中读取字符集，并识别出字符集中的每一个字符。假设字符集的总字符数为n，利用这个n个字符组成长为n的字符串。其中每个字符均可重复使用，每个字符串中也不必包含全部字符。试求出所有长为n的字符串集合。最后将所求的的集合写入文件“result.txt”中。

程序输入输出样例

– data.txt中的内容为

@#

– result.txt中的内容为

@@

@#

#@

##

枚举 递归     卡了半天，纯粹的弱智不解释。。。。。

//
//  main.cpp
//  str
//
//  Created by Bryan on 14-6-28.
//  Copyright (c) 2014年 Bryan. All rights reserved.
//#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <fstream>
#include <list>using namespace std;list<char> GetCharsFromFile()
{ifstream inFile("data.txt");list<char> ret;if(inFile){string s;getline(inFile,s);for(int i = 0;i<s.length();i++){ret.push_back(s[i]);}ret.sort();ret.unique();inFile.close();return ret;}return ret;
}void CharCombination(vector<string> &strVec,list<char> &charList,char *s,int step)
{if(step == charList.size()){s[step] = '\0';string stmp(s);strVec.push_back(stmp);return;}for(list<char>::iterator it = charList.begin();it != charList.end();it++){s[step] = *it;CharCombination(strVec,charList ,s, step + 1);}}int main(int argc, const char * argv[])
{list<char> charList;charList = GetCharsFromFile();vector<string> ret;char *cstr = new char[charList.size() + 1];CharCombination(ret,charList, cstr,0);ofstream outFile;outFile.open("result.txt");for(int i = 0;i<ret.size();i++)outFile<<ret[i]<<endl;outFile.close();return 0;
}

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>using namespace std;void func(vector<char> & s,char *ret,int k,int N,ofstream &outFile)
{if(k == N ){ret[N] = '\0';cout<<ret<<endl;outFile<<ret<<endl;return;}for(int i = 0;i<N;i++){ret[k] = s[i];func(s,ret,k+1,N,outFile);}
}
int main()
{ifstream inFileStream;inFileStream.open("data.txt");ofstream outFileStream;outFileStream.open("result.txt");char *str = new char[1000];inFileStream.getline(str,1000);vector<char> vec;for(int i = 0;i<1000;i++){if(str[i] != '\0')vec.push_back(str[i]);elsebreak;}int N = vec.size();char * ret = new char[N+1];func(vec,ret,0,N,outFileStream);inFileStream.close();outFileStream.close();getchar();}

#include <iostream>
#include <fstream>
#include <string>
#include <vector>using namespace std;void func(const vector<char> &charVec,char* finalStr,ofstream & outFile,int k,int N)
{if(k==N){finalStr[N]= '\0';cout<<finalStr<<endl;outFile<<finalStr<<endl;return;}for(int i= 0;i<N;i++){finalStr[k] = charVec[i];func(charVec,finalStr,outFile,k+1,N);}
}int main()
{ofstream outFile;outFile.open("result.txt");ifstream inFile;inFile.open("data.txt");string inStr;vector<char> charVec;outFile<<"The chars are: ";cout<<"The chars are: ";while(getline(inFile,inStr)){for(string::iterator it = inStr.begin();it != inStr.end();it++){cout<<(*it)<<" ";outFile<<(*it)<<" ";charVec.push_back(*it);}}cout<<endl;int N = charVec.size();char* outStr =new char[N+1];func(charVec,outStr,outFile,0,N);outFile.close();inFile.close();getchar();
}

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