BZOJ 3109([cqoi2013]新数独-搜索)

虽然想DLX可是建不出图……
话说最近做了很多看着不可做，最后搜索过的题。。

#include<bits/stdc++.h>using namespace std;#define For(i,n) for(int i=1;i<=n;i++)#define Fork(i,k,n) for(int i=k;i<=n;i++)#define Rep(i,n) for(int i=0;i<n;i++)#define ForD(i,n) for(int i=n;i;i--)#define ForkD(i,k,n) for(int i=n;i>=k;i--)#define RepD(i,n) for(int i=n;i>=0;i--)#define Forp(x) for(int p=Pre[x];p;p=Next[p])#define Forpiter(x) for(int &p=iter[x];p;p=Next[p])  #define Lson (o<<1)#define Rson ((o<<1)+1)#define MEM(a) memset(a,0,sizeof(a));#define MEMI(a) memset(a,0x3f,sizeof(a));#define MEMi(a) memset(a,128,sizeof(a));#define MEMx(a,b) memset(a,b,sizeof(a));#define INF (0x3f3f3f3f)#define F (100000007)#define pb push_back#define mp make_pair #define fi first#define se second#define vi vector<int> #define pi pair<int,int>#define SI(a) ((a).size())#define Pr(kcase,ans) printf("Case #%d: %lld\n",kcase,ans);#define PRi(a,n) For(i,n-1) cout<<a[i]<<' '; cout<<a[n]<<endl;#define PRi2D(a,n,m) For(i,n) { \                        For(j,m-1) cout<<a[i][j]<<' ';\                        cout<<a[i][m]<<endl; \                        } #pragma comment(linker, "/STACK:102400000,102400000")typedef long long ll;typedef long double ld;typedef unsigned long long ull;ll mul(ll a,ll b){return (a*b)%F;}ll add(ll a,ll b){return (a+b)%F;}ll sub(ll a,ll b){return ((a-b)%F+F)%F;}void upd(ll &a,ll b){a=(a%F+b%F)%F;}int read(){    int x=0,f=1; char ch=getchar();    while(!isdigit(ch)) {if (ch=='-') f=-1; ch=getchar();}    while(isdigit(ch)) { x=x*10+ch-'0'; ch=getchar();}    return x*f;} #define MAXN (20)int lef[MAXN][MAXN],up[MAXN][MAXN];int get() {    char c[2];    cin>>c;    if (c[0]=='<'||c[0]=='^') return 0;    return 1;} bool br[MAXN][MAXN]={0},bc[MAXN][MAXN]={0},bb[MAXN][MAXN]={0};int f[MAXN][MAXN];bool check(int i,int j,int v) {    if (j%3) if ((lef[i][j-1]==1)^(f[i][j-1]>v) ) return 0;    if (i%3) if (up[i-1][j] ^ (f[i-1][j]>v) ) return 0;    return 1;} void dfs(int x,int y) {    if (x==9) {        Rep(i,9){            Rep(j,8) printf("%d ",1+f[i][j]);            printf("%d\n",1+f[i][8]);        }        exit(0);    }    Rep(v,9) {        if ( br[x][v] || bc[y][v] || bb[x/3*3+y/3][v] || !check(x,y,v) )  continue;        br[x][v] = bc[y][v] = bb[x/3*3+y/3][v] =1;        f[x][y]=v;        if (y<8) dfs(x, y+1 ); else dfs(x+1,0);        br[x][v] = bc[y][v] = bb[x/3*3+y/3][v] =0;    }}int main(){//  freopen("bzoj3109.in","r",stdin);//  freopen(".out","w",stdout);    MEMx(lef,-1) MEMx(up,-1)    Rep(i,9) {        Rep(j,9) if (j%3!=2) lef[i][j]=get();        if (i%3!=2)            Rep(j,9) up[i][j]=get();     }    dfs(0,0);    return 0;}