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我用C++ class结构，写了个关于第三题的程序。楼主可以参考。

#include
#include
#include
#include
#include


using namespace std;



//Constructor use -1 to terminate parameter;
//like CalcMoney(100,1,2,5,-1);
class CalcMoney
{
friend int main(int argc,char *argv[]); //use for debug
private:
int nWays;
int TotalMoney;
int size;
vector vMoney;
vector vMaxCount;
vector vCount;
protected:
void DisplayMoney();
public:
CalcMoney(int,int,...);

void PutThingsTogether();

void Init();
void DoTheSort();
void CalcMaxCount();
void Calculate(int level,int sum);

int Show();


};

CalcMoney::CalcMoney(int Money=100,int first=1,...)
{
size=1;
va_list pos;
int argument;

TotalMoney=Money;

vMoney.push_back(first);

va_start(pos,first);
while( (argument=va_arg(pos,int))!=-1 )
{
vMoney.push_back(argument);
size++;
}
}

void CalcMoney::PutThingsTogether()
{
Init();
DoTheSort();
CalcMaxCount();

cout << "The total money is: " << TotalMoney << "\n";
cout << "The change is: \n";
for(int i=0;i cout << vMoney[i] << "\t";
cout << "\n";
cout << "----------------------------";
cout << endl;

Calculate(0,0);
}

void CalcMoney::Init()
{
vCount.resize(size);

nWays=0;
}

void CalcMoney::DoTheSort()
{
sort(vMoney.begin(),vMoney.end(),greater());
}

void CalcMoney::CalcMaxCount()
{
for(int i=0;i vMaxCount.push_back(TotalMoney/vMoney[i]);
}


void CalcMoney::Calculate(int level,int sum)
{
int PartSum;
if(level==size)
return;
for(int i=0;i<=vMaxCount[level];i++)
{
vCount[level]=i;

PartSum=i*vMoney[level];

if(sum+PartSum==TotalMoney)
{
nWays++;

//print the result
for(int j=0;j<=level;j++)
cout << vCount[j] << "\t";
cout << endl;
continue;
}

Calculate(level+1,sum+PartSum);
}

}

void CalcMoney::DisplayMoney()
{
vector::iterator iter;
for(iter=vMoney.begin();iter!=vMoney.end();iter++)
cout << *iter << "\n";
cout << endl;
}

int CalcMoney::Show()
{
return nWays;
}

int main(int argc,char *argv[])
{
CalcMoney cm(100,1,2,5,-1);
cm.PutThingsTogether();
cout << "There are " << cm.Show() << " ways." << endl;

return 0;
}

事实上以上程序，最重要的是Calculate()递归函数。如果按C的风格，只要这个函数就OK了。但是为了练习一下C＋＋，呵呵。如果有疑问可以提出。声明一下，我不是C＋＋高手。进来纯属好奇。

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