2110 ACM Crisis of HDU 母函数

题目：http://acm.hdu.edu.cn/showproblem.php?pid=2110

题意：分出1/3的价值，有几种可能？

思路：母函数

与之前的题目2079相似，复习笔记再来写代码：

https://www.cnblogs.com/CheeseIce/p/9595315.html

代码：

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

#define min(a,b) ((a)<(b)?(a):(b))

int N,n[],v[],i,last,last2,sum;
int a[],b[];

int main()
{
    while ((cin>>N)&&N!=)
    {
        sum=;
        for (i=;i<N;i++)
        {
            cin>>v[i]>>n[i];
            sum+=v[i]*n[i];
        }
        if (sum%!=)
        {
            cout<<"sorry"<<endl;
            continue;
        }
        sum/=;
        a[]=;
        last=;
        int j,k;
        for (i=;i<N;i++)
        {
            last2=min(last+n[i]*v[i],sum);
            memset(b,,sizeof(int)*(last2+));
            for (j=;j<=n[i]&&j*v[i]<=last2;j++)
                for (k=;k<=last&&k+j*v[i]<=last2;k++)
                {
                    b[k+j*v[i]]+=a[k];
                    b[k+j*v[i]]%=;
                }
            memcpy(a,b,sizeof(int)*(last2+));
            last=last2;
        }
        if (a[sum]>)
            cout<<a[sum]<<endl;
        else
            cout<<"sorry"<<endl;
    }
}