# [DLX precise coverage] HDU 1603 A puzzling problem

Source: Internet
Author: User

Test instructions

Give you n pieces of debris that cannot be rotated or folded.

Ask if you can use some of these pieces to spell out 4*4 squares.

Ideas:

Cover the naked question exactly.

The map is to see where each fragment can be placed in the 4*4, as a row.

The column is 4*4=16, plus n fragments, which is 16+n.

and pay attention to the established decision.

Code:

`#include "stdio.h" #include "algorithm" #include "string.h" #include "iostream" #include "queue" #include "map" #include "    Vector "#include" string "using namespace std; #define N 1005*1005#define RN 1005#define M 1005struct dlx{int n,m,c;    int u[n],d[n],l[n],r[n],row[n],col[n];    int h[m],s[m],cnt,ans[m];        void init (int _n,int _m) {n=_n;        M=_m;            for (int i=0; i<=m; i++) {u[i]=d[i]=i;            L[i]= (i==0?m:i-1);            R[i]= (i==m?0:i+1);        s[i]=0;        } c=m;    for (int i=1; i<=n; i++) h[i]=-1;        } void link (int x,int y) {C + +;        Row[c]=x;        Col[c]=y;        s[y]++;        U[c]=u[y];        D[c]=y;        D[u[y]]=c;        U[y]=c;        if (h[x]==-1) h[x]=l[c]=r[c]=c;            else {l[c]=l[h[x]];            R[C]=H[X];            R[l[h[x]]]=c;        L[h[x]]=c;        }} void del (int x) {r[l[x]]=r[x];        L[R[X]]=L[X];  for (int i=d[x]; i!=x; I=d[i])      {for (int j=r[i]; j!=i; J=r[j]) {u[d[j]]=u[j];                D[U[J]]=D[J];            s[col[j]]--; }}}} void rec (int x) {for (int. i=u[x]; i!=x; I=u[i]) {for (int j=l[i]; j!=i; j=l                [j]) {u[d[j]]=j;                D[u[j]]=j;            s[col[j]]++;        }} r[l[x]]=x;    L[r[x]]=x; } int Dance (int x) {if (r[0]==0 | |            R[0]&GT;16) {cnt=x;        return 1;        } int now=r[0];        for (int i=r[0]; i!=0 && i<=16; i=r[i]) {if (S[i]<s[now]) now=i;        } del (now);            for (int i=d[now]; i!=now; I=d[i]) {ans[x]=row[i];            for (int j=r[i]; j!=i; J=r[j] del (col[j]);            if (dance (x+1)) return 1;        for (int j=l[i]; j!=i; j=l[j]) rec (col[j]);        } rec (now);    return 0; }} dlx;struct node{intM,id; int w[44];}    Kx[1234];int Main () {int n;        while (scanf ("%d", &n), n) {int cnt=0;        Dlx.init (N*16,16+n);            for (int i=1; i<=n; i++) {int A, B;            scanf ("%d%d", &a,&b);            Char v[12][12];            for (int j=0; j<a; j + +) scanf ("%s", V[j]);                    for (int xx=1, xx+a<=5; xx++) {for (int yy=1; yy+b<=5; yy++) {                    cnt++;                    kx[cnt].m=0;                    Kx[cnt].id=i;                            for (int x=0; x<a; x + +) {for (int y=0; y<b; y++) { if (v[x][y]== ' 1 ') {int tep= (xx+x-1) *4+                                (Yy+y);                                Dlx.link (Cnt,tep);                            Kx[cnt].w[kx[cnt].m++]=tep;                }                        }                    }    Dlx.link (Cnt,16+i);        }}} int f=dlx.dance (0);        if (f==0) puts ("No solution possible");            else {char mp[10][10];                    for (int i=0;i<dlx.cnt;i++) {for (int j=0;j<kx[dlx.ans[i]].m;j++) {                    int x, y;                    x= (kx[dlx.ans[i]].w[j]-1)/4;                    Y=kx[dlx.ans[i]].w[j]%4-1;                    if (y==-1) y=3;                mp[x][y]=kx[dlx.ans[i]].id+ ' 0 ';                }} for (int i=0;i<4;i++) {mp[i][4]= ');            Puts (Mp[i]);    }} puts (""); } return 0;}`

[DLX precise coverage] HDU 1603 A puzzling problem

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