字符串组合递归求解

一 问题描述：

输入字符串，如abcde，求它的3的组合

二：代码

/*This is a free Program, You can modify or redistribute it under the terms of GNU*Description:字符串组合递归求解*Language: C++*Development Environment: VC6.0*Author: Wangzhicheng*E-mail: [e-mail]*Date: 2012/12/14*/#include <iostream>#include <string>#include <cstdlib>using namespace std;/**Solution类封装了使用了递归的组合算法*str:指向当前用户输入的字符串*tmp:指向组合的字符串*selectM:选取几个数来组合*/class Solution {private:char *str;char *tmp;int selectM;/**递归实现组合*selectStart:指向str中当前被操作的字符*selectCur:指向tmp中当前被操作的字符*/void Combine(int selectStart,int selectCur) {static int cnt;if(selectCur>=selectM) {               //一种新的组合产生cout<<"第"<<++cnt<<"种组合是:"<<tmp<<endl;}else {int i;for(i=selectStart;str[i];i++) {tmp[selectCur]=str[i];Combine(i+1,selectCur+1);}}}public:Solution(const char *string,int selectM) {int n=strlen(string);str=new char[n+1];if(!str) exit(1);strncpy(str,string,n+1);this->selectM=selectM;tmp=new char[selectM+1];if(!tmp) exit(1);tmp[selectM+1]='\0';}void Combine() {Combine(0,0);}};void main() {Solution s("abcdef",2);s.Combine();}

 

三 测试