【转帖】0-1背包：纸币组合

    有不限数目的1、5、10、20、50面额的纸币，有多少种方法凑出100元？

    笨办法：暴力枚举~

#include<iostream>
#include<cstring>
using namespace std;

const int Len = 5;
int ans = 0;
int m[Len] = {50, 20, 10, 5, 1};
int total[Len] = {2, 5, 10, 20, 100};
int n[Len];
int sum = 100;

void GetNum(int m[], int n[])
{　 //方法一：类似于n位k进制枚举，电话号码单词
    while (true)
    {
        int rel = 0;
        for (int i = 0; i < 5; i++)
            rel += m[i] * n[i];
        if (rel == sum)
        {
            ans++;
            for (int i = 0; i < Len; i++)
                cout << n[i] << " ";
            cout << endl;
        }

        int k = Len - 1;
        while (k >= 0)
        {
            if (n[k] < total[k])
            {
                n[k]++;
                break;
            }
            else
            {
                n[k] = 0;
                k--;
            }
        }
        if (k < 0)
            break;
    }

}

void RecursiveGetNum(int m[], int n[], int index)
{   //方法二：recursion
    if (index == Len)
    {
        int rel = 0;
        for (int i = 0; i < Len; i++)
            rel += m[i] * n[i];
        if (rel == sum)
        {
            ans++;
            for (int i = 0; i < Len; i++)
                cout << n[i] << " ";
            cout << endl;
        }
        return;
    }
    for (n[index] = 0; n[index] <= total[index]; n[index]++)
    {
        RecursiveGetNum(m, n, index + 1);
    }

}

int main()
{
    GetNum(m, n);
    //RecursiveGetNum(m, n, 0);
    cout << ans << endl;
    return 0;
}