Healthy Holsteins chapter 2.1

  dfs+枚举,最近发现dfs+保存中间过程+dfs前后回复变量 ,简直是太好用了,主要剪枝是:对于已用feeds种类==已知最小种类 先判断 然后直接在dfs里return,剪掉了>与已知种类的dfs

结果还是蛮高兴的

Executing...
   Test 1: TEST OK [0.000 secs, 3500 KB]
   Test 2: TEST OK [0.011 secs, 3500 KB]
   Test 3: TEST OK [0.000 secs, 3500 KB]
   Test 4: TEST OK [0.000 secs, 3500 KB]
   Test 5: TEST OK [0.000 secs, 3500 KB]
   Test 6: TEST OK [0.000 secs, 3500 KB]
   Test 7: TEST OK [0.000 secs, 3500 KB]
   Test 8: TEST OK [0.000 secs, 3500 KB]
   Test 9: TEST OK [0.000 secs, 3500 KB]
   Test 10: TEST OK [0.000 secs, 3500 KB]

All tests OK.

YOUR PROGRAM ('holstein') WORKED FIRST TIME! That's fantastic -- and a rare thing. Please accept these special automated congratulations.

/*

ID: hubiao cave

PROG: holstein

LANG: C++

*/




#include<iostream>

#include<fstream>

#include<string>

using namespace std;


int vnum;
int vneed[27];
int fnum;
int feeds[17][27];
bool used[17];
int minik=999;
int tstep;

int usedfeed[17];
int tempfeed[17];

void dfs(int);
bool canfit();

int main()

{




    ifstream fin("holstein.in");

    ofstream fout("holstein.out");
    fin>>vnum;
    for(int i=1;i<=vnum;i++)
    {
        fin>>vneed[i];
    }

    fin>>fnum;
    for(int i=1;i<=fnum;i++)
    {
        for(int j=1;j<=vnum;j++)
            fin>>feeds[i][j];
    }
    dfs(1);
    fout<<minik;
    for(int i=1;i<=minik;i++)
        fout<<" "<<usedfeed[i];
    fout<<endl;

    return 0;


}

void dfs(int n)
{
    if(tstep==minik)
    {
        if(!canfit())
            return;
        else
        {
            for(int i=1;i<=tstep;i++)
            {
                if(tempfeed[i]==usedfeed[i])
                    continue;
                if(tempfeed[i]>usedfeed[i])
                    return;
                if(tempfeed[i]<usedfeed[i])
                {
                    for(int j=i;j<=tstep;j++)
                        usedfeed[j]=tempfeed[j];
                    return;
                }

            }
        }
    }

    if(n<=fnum)
    {
    for(int i=0;i<=1;i++)
    {
        if(used[n]=i)
        {
            tstep++;
            tempfeed[tstep]=n;
            dfs(n+1);
            tstep--;
            used[n]=0;
        }
        else
         dfs(n+1);
    }
    }
    else
    {

        if(canfit())
        {
            if(tstep<minik)
            {
                minik=tstep;
                for(int i=1;i<=tstep;i++)
                {
                    usedfeed[i]=tempfeed[i];
                }
            }

        }

    }

}

bool canfit()
{
    for(int i=1;i<=vnum;i++)
    {
        int t=0;
        for(int j=1;j<=fnum;j++)
        {
            t+=feeds[j][i]*(int)used[j];
        }

        if(t<vneed[i])
            return false;
    }
    return true;
}