HDU1085 —— 生成函数入门题

(1+X^i)*……

最经典的生成函数。

#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
typedef long long ll;
#define ls (o<<1)
#define rs (o<<1|1)
#define pb push_back

const int M = 1e4+7;
/*
int head[M],cnt=1;
void init(){cnt=1,memset(head,0,sizeof(head));}
struct EDGE{int to,nxt,w;}ee[M*2];
void add(int x,int y,int w){ee[++cnt].nxt=head[x],ee[cnt].w=w,ee[cnt].to=y,head[x]=cnt;}
*/
int f[4][M];
int w[4]={0,1,2,5};
int vs[M],nm[4];
int main()
{
	ios::sync_with_stdio(false);
  	cin.tie(0);
  	while(1)
	{
		cin>>nm[1]>>nm[2]>>nm[3];
		if(nm[1]==0&&nm[2]==0&&nm[3]==0)break;
	  	vector<int>v;
	  	v.pb(0);
	  	memset(f,0,sizeof(f));
	  	memset(vs,0,sizeof(vs));
	  	f[0][0]=vs[0]=1;
	  	for(int i=1;i<=3;i++)
	  	{
	  		vector<int>tp;
	  		for(auto x:v)
	  		{
	  			for(int k=0;k<=nm[i];k++)
	  			{
	  			//	cout<<i<<" "<<x<< "  "<<k<<" "<<x+k*w[i]<<endl;
	  				f[i][x+k*w[i]]+=f[i-1][x];
	  				if(!vs[x+k*w[i]])vs[x+k*w[i]]=1,tp.pb(x+k*w[i]);
					  //cout<<"==-=-=    "<<x+k*w[i]<<endl;;
				}
			}
			for(auto x:tp)v.pb(x);
		}
		for(int i=1;i<=10000;i++)if(f[3][i]==0){
			cout<<i<<endl;
			break;
		}
	}
	return 0;
}

 

本文地址：https://blog.csdn.net/bjfu170203101/article/details/107592665