最近面試的算法題目

一個集合x有都不相同的n個元素，使用這個集合中的不定個數的元素，組成一個和為s的序列，求出所有符合的序列，元素可以重復使用，只要元素的個數相同不考慮順序。

比如集合是x={2,3,4,5,7}; n=5, s=12可以得出以下的序列：

2       2       2       2       2       2
2       2       2       2       4
2       2       2       3       3
2       2       3       5
2       2       4       4
2       3       3       4
2       3       7
2       5       5
3       3       3       3
3       4       5
4       4       4
5       7

#include <iostream>   
#include <vector>   
using namespace std;  
int PushVector(int *x,int n,int s,vector<int> &tablelist,int Position)  
{  
    if(s<0)  
    {  
        tablelist.clear();  
        return 0;  
    }  
    else if(s==0)  
    {  
        for(int i=0;i<tablelist.size();i++)  
        {  
            cout<<tablelist[i]<<"\t";  
        }  
        cout<<"\n";  
          
        return 0;  
    }  
    else if(s>0)  
    {  
        for(int i=Position;i<n;i++)  
        {  
            vector<int> newtablelist;  
            for (int j=0;j<tablelist.size();j++)  
            {  
                newtablelist.push_back(tablelist[j]);  
            }  
            newtablelist.push_back(x[i]);  
            int news = s-x[i];  
            //cout<<i<<","<<news<<"\n";   
            PushVector(x,n,news,newtablelist,i);  
        }  
  
  
    }  
    else  
    {  
  
  
    }  
    return 0;  
}  
  
  
/* run this program using the console pauser or add your own getch, system("pause") or input loop */  
int FindResult(int * x,int n,int s)  
{  
    vector<int> tablelist;  
    tablelist.clear();  
    PushVector(x,n,s,tablelist,0);  
    return 0;  
}  
  
  
  
  
int main(int argc, char** argv)   
{  
    int x[]= {2,3,4,5,7};  
    int n =5;  
    int s=12;  
    FindResult(x,n,s);  
    system("pause");  
    return 0;  
}  

#include <iostream>
#include <vector>
using namespace std;
int PushVector(int *x,int n,int s,vector<int> &tablelist,int Position)
{
	if(s<0)
	{
		tablelist.clear();
		return 0;
	}
	else if(s==0)
	{
		for(int i=0;i<tablelist.size();i++)
		{
			cout<<tablelist[i]<<"\t";
		}
		cout<<"\n";
		
		return 0;
	}
	else if(s>0)
	{
		for(int i=Position;i<n;i++)
		{
			vector<int> newtablelist;
			for (int j=0;j<tablelist.size();j++)
			{
				newtablelist.push_back(tablelist[j]);
			}
			newtablelist.push_back(x[i]);
			int news = s-x[i];
			//cout<<i<<","<<news<<"\n";
			PushVector(x,n,news,newtablelist,i);
		}


	}
	else
	{


	}
	return 0;
}


/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int FindResult(int * x,int n,int s)
{
	vector<int> tablelist;
	tablelist.clear();
	PushVector(x,n,s,tablelist,0);
	return 0;
}




int main(int argc, char** argv) 
{
	int x[]= {2,3,4,5,7};
	int n =5;
	int s=12;
	FindResult(x,n,s);
	system("pause");
	return 0;
}