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; }