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poj 1084 Square Destroyer dlx解重复覆盖

热度:47   发布时间:2024-01-19 05:42:11.0

分析:

将问题转化为重复覆盖问题,DancingLink解决。

代码:

//poj 1084
//sep9
#include <iostream>
using namespace std;
const int maxN=10024;
const int maxL=128;
int L[maxN],R[maxN],U[maxN],D[maxN];
int C[maxN],H[maxN];
int S[maxN],A[maxN],X[maxN];
bool makeup[maxL][maxL];
int cnt,ans;
void build(int r,int c)
{for(int i=0;i<=c;++i){U[i]=D[i]=i;L[i]=i==0?c:i-1;R[i]=(i+1)%(c+1);C[i]=i;//colum head's idS[i]=0;}for(int i=1;i<=r;++i)H[i]=-1;//row head's id;	cnt=c;
}void init(int n)
{memset(makeup,false,sizeof(makeup));int c=1;for(int len=1;len<=n;++len)for(int i=1;i+len<=n+1;++i)for(int j=1;j+len<=n+1;++j){for(int k=0;k<len;++k){makeup[(i-1)*(2*n+1)+j+k][c]=true;					makeup[(i-1+len)*(2*n+1)+j+k][c]=true;makeup[i*n+(i-1)*(n+1)+j+k*(2*n+1)][c]=true;makeup[i*n+(i-1)*(n+1)+j+k*(2*n+1)+len][c]=true;}	c++;}
}void link(int r,int c)
{++cnt;C[cnt]=c;++S[c];	X[cnt]=r;D[cnt]=D[c];U[D[c]]=cnt;D[c]=cnt;U[cnt]=c;if(H[r]<0)H[r]=L[cnt]=R[cnt]=cnt;else{R[cnt]=R[H[r]];L[cnt]=H[r];L[R[H[r]]]=cnt;R[H[r]]=cnt;}
}void remove(int c)
{for(int i=D[c];i!=c;i=D[i]){L[R[i]]=L[i];R[L[i]]=R[i];}	
} void resume(int c)
{for(int i=D[c];i!=c;i=D[i]){L[R[i]]=i;R[L[i]]=i;}	
}int get_H()
{bool has[maxL];memset(has,false,sizeof(has));int res=0;for(int i=R[0];i!=0;i=R[i])if(!has[i]){++res;for(int j=D[i];j!=i;j=D[j])for(int k=R[j];k!=j;k=R[k])has[C[k]]=true;}	return res;
}void dfs(int k)
{if(R[0]==0){ans=min(ans,k);return ;}else if(k+get_H()>=ans)return ;int c=R[0];for(int t=R[0],maxx=INT_MAX;t!=0;t=R[t])if(S[t]<maxx)maxx=S[t],c=t;					for(int i=D[c];i!=c;i=D[i]){remove(i);for(int j=R[i];j!=i;j=R[j]){remove(j);--S[C[j]];}dfs(k+1);for(int j=L[i];j!=i;j=L[j]){resume(j);++S[C[j]];}resume(i);			}		
}int main()
{int cases,n,row,col;scanf("%d",&cases);while(cases--){scanf("%d",&n);	col=0,row=2*n*(n+1);for(int i=1;i<=n;++i)col+=i*i;build(row,col);init(n);int num;scanf("%d",&num);bool vis[maxL];//mark square have been destoryedmemset(vis,false,sizeof(vis));while(num--){int r;scanf("%d",&r);for(int j=1;j<=col;++j)if(makeup[r][j]&&!vis[j]){vis[j]=true;R[L[j]]=R[j];L[R[j]]=L[j];}				}for(int i=1;i<=row;++i)for(int j=1;j<=col;++j)if(makeup[i][j]&&!vis[j])link(i,j);ans=INT_MAX;dfs(0);printf("%d\n",ans);}return 0;	
}