USACO s2.1 Health Holsteins

题目大意:给出牛所需各类维他命的量,和各种稻草所含的各类维他命的量.每种稻草使用一次,求最少组合使用哪几种稻草可满足牛的维他命需求.相同数量按字典序.

思路:深搜剪枝.

按顺序深搜,则第一个满足的为该层的解.不必再往本层和下一层搜.

 

/*ID:sheshao1LANG:CTASK:holstein*/#include <stdio.h>int dig[]={1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536};int req[26],rec[26];int type[16][26];int V,G,m,ans;void dfs(int r,int dep,int next);int main(){FILE *fin,*fout;int i,j;fin = fopen("holstein.in","r");fout = fopen("holstein.out","w");/* 1<=V<=25 */fscanf(fin,"%d",&V);for(i=0;i<V;i++)fscanf(fin,"%d",&req[i]);/* 1<=G<=15*/fscanf(fin,"%d",&G);for(i=G-1;i>=0;i--)for(j=0;j<V;j++)fscanf(fin,"%d",&type[i][j]);m=20;for(i=G-1;i>=0 && m>1;i--){for(j=0;j<V;j++)rec[j]=type[i][j];dfs(dig[i],1,i-1);}fprintf(fout,"%d ",m);for(i=1;i<=G,m;i++){ if(ans & dig[G-i]){ m--; if(m) fprintf(fout,"%d ",i); else fprintf(fout,"%d/n",i); } } return 0;}void dfs(int r,int dep,int next){int i,j;for(i=0;i<V;i++)if(rec[i]<req[i])break;if(i==V){m=dep;ans=r;return ;}for(i=next,dep++;i>=0 && dep<m;i--){for(j=0;j<V;j++)rec[j]+=type[i][j];dfs(r+dig[i],dep,i-1);for(j=0;j<V;j++)rec[j]-=type[i][j];}}/*Compile: OKExecuting... Test 1: TEST OK [0.000 secs, 1976 KB] Test 2: TEST OK [0.000 secs, 1976 KB] Test 3: TEST OK [0.000 secs, 1976 KB] Test 4: TEST OK [0.000 secs, 1976 KB] Test 5: TEST OK [0.000 secs, 1976 KB] Test 6: TEST OK [0.000 secs, 1976 KB] Test 7: TEST OK [0.000 secs, 1976 KB] Test 8: TEST OK [0.000 secs, 1976 KB] Test 9: TEST OK [0.000 secs, 1976 KB] Test 10: TEST OK [0.000 secs, 1976 KB]All tests OK.*/