POJ 3740 精确覆盖 模板

//#pragma comment(linker, "/STACK:102400000,102400000")#include<cstdio>#include<cstring>#include<vector>#include<queue>#include<cmath>#include<cctype>#include<string>#include<algorithm>#include<iostream>#include<ctime>#include<map>#include<set>using namespace std;#define MP(x,y) make_pair((x),(y))#define PB(x) push_back(x)typedef __int64 LL;//typedef unsigned __int64 ULL;/* ****************** */const int INF=1000111222;const double INFF=1e100;const double eps=1e-8;//const LL mod=1000000007;const int NN=305;const int MM=2000010;/* ****************** */const int maxn=305;const int maxr=20;const int maxnode=305*20;int sz;int ans[maxr],ansd;int S[maxn],dl_qw[maxn];int row[maxnode],col[maxnode];int L[maxnode],R[maxnode],U[maxnode],D[maxnode];void dl_init(int n){    int i;    for(i=0;i<=n;i++)    {        U[i]=D[i]=i;        L[i]=i-1;        R[i]=i+1;        S[i]=0;    }    L[0]=n;    R[n]=0;    sz=n+1;}/* cnt>0!!!! */void dl_add(int r,int cnt){    int i,first=sz;    for(i=0;i<cnt;i++)    {        int c=dl_qw[i];        L[sz]=sz-1;        R[sz]=sz+1;        U[sz]=U[c];        D[sz]=c;        D[ U[c] ]=sz;        U[c]=sz;        row[sz]=r;        col[sz]=c;        S[c]++;        sz++;    }    L[first]=sz-1;    R[sz-1]=first;}/* 删除c列 *//* L,R只用删最上面的就好，其他点删U,D就好了 */void remove(int c){    int i,j;    L[R[c]]=L[c];    R[L[c]]=R[c];    for(i=D[c];i!=c;i=D[i])        for(j=R[i];j!=i;j=R[j])        {            U[D[j]]=U[j];            D[U[j]]=D[j];            --S[col[j]];        }}/* 与remove顺序是相反的 */void restore(int c){    int i,j;    for(i=U[c];i!=c;i=U[i])        for(j=L[i];j!=i;j=L[j])        {            ++S[col[j]];            U[D[j]]=j;            D[U[j]]=j;        }    L[R[c]]=c;    R[L[c]]=c;}bool dl_dfs(int d){    if(R[0]==0)    {        ansd=d;        return true;    }    int i,j,c=R[0];    for(i=R[0];i!=0;i=R[i])        if(S[i]<S[c])            c=i;    remove(c);    for(i=D[c];i!=c;i=D[i])    {        ans[d]=row[i];        for(j=R[i];j!=i;j=R[j])            remove(col[j]);        if(dl_dfs(d+1))            return true;        for(j=L[i];j!=i;j=L[j])            restore(col[j]);    }    restore(c);    return false;}int main(){    int n,m,i,j,toll,t;    while(scanf("%d%d",&n,&m)!=EOF)    {        dl_init(m);        for(i=1;i<=n;i++)        {            toll=0;            for(j=1;j<=m;j++)            {                scanf("%d",&t);                if(t)                {                    dl_qw[toll++]=j;                }            }            if(toll>0)                dl_add(i,toll);        }        if(dl_dfs(0))            puts("Yes, I found it");        else            puts("It is impossible");    }    return 0;}