P1074 靶形数独（爆搜）

Posted 2022-11-23 oneman233

说是爆搜，却还是有点技巧

首先数独应该有个想法，从最有可能填上数字的那些地方开始

也就是说哪些行0最少，就从那儿开始

为了最大限度地利用已有信息，就先把所有0的位置扣出来单独填

最后别忘了回溯就行

但是这种做法仍然过不了下面这个样例：

0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0

还是应该学学DLX，此外用拼音做数组名实在太爽了

代码：

#include <bits/stdc++.h>
#define int long long
#define sc(a) scanf("%lld",&a)
#define scc(a,b) scanf("%lld %lld",&a,&b)
#define sccc(a,b,c) scanf("%lld %lld %lld",&a,&b,&c)
#define scs(a) scanf("%s",a) 
#define schar(a) scanf("%c",&a)
#define pr(a) printf("%lld",a)
#define fo(i,a,b) for(int i=a;i<b;++i)
#define re(i,a,b) for(int i=a;i<=b;++i)
#define rfo(i,a,b) for(int i=a;i>b;--i)
#define rre(i,a,b) for(int i=a;i>=b;--i)
#define prn() printf("\n")
#define prs() printf(" ")
#define mkp make_pair
#define pii pair<int,int>
#define pub(a) push_back(a)
#define pob() pop_back()
#define puf(a) push_front(a)
#define pof() pop_front()
#define fst first
#define snd second
#define frt front()
#define bak back()
#define mem0(a) memset(a,0,sizeof(a))
#define memmx(a) memset(a,0x3f3f,sizeof(a))
#define memmn(a) memset(a,-0x3f3f,sizeof(a))
#define debug
#define db double
#define yyes cout<<"YES"<<endl;
#define nno cout<<"NO"<<endl;
using namespace std;
typedef vector<int> vei;
typedef vector<pii> vep;
typedef map<int,int> mpii;
typedef map<char,int> mpci;
typedef map<string,int> mpsi;
typedef deque<int> deqi;
typedef deque<char> deqc;
typedef priority_queue<int> mxpq;
typedef priority_queue<int,vector<int>,greater<int> > mnpq;
typedef priority_queue<pii> mxpqii;
typedef priority_queue<pii,vector<pii>,greater<pii> > mnpqii;
const int maxn=500005;
const int inf=0x3f3f3f3f3f3f3f3f;
const int MOD=100000007;
const db eps=1e-10;
int qpow(int a,int b)int tmp=a%MOD,ans=1;while(b)if(b&1)ans*=tmp,ans%=MOD;tmp*=tmp,tmp%=MOD,b>>=1;return ans;
int lowbit(int x)return x&-x;
int max(int a,int b)return a>b?a:b;
int min(int a,int b)return a<b?a:b;
int mmax(int a,int b,int c)return max(a,max(b,c));
int mmin(int a,int b,int c)return min(a,min(b,c));
void mod(int &a)a+=MOD;a%=MOD;
bool chk(int now)
int half(int l,int r)while(l<=r)int m=(l+r)/2;if(chk(m))r=m-1;else l=m+1;return l;
int ll(int p)return p<<1;
int rr(int p)return p<<1|1;
int mm(int l,int r)return (l+r)/2;
int lg(int x)if(x==0) return 1;return (int)log2(x)+1;
bool smleql(db a,db b)if(a<b||fabs(a-b)<=eps)return true;return false;
bool bigeql(db a,db b)if(a>b||fabs(a-b)<=eps)return true;return false;
bool eql(db a,db b)if(fabs(a-b)<eps) return 1;return 0;
db len(db a,db b,db c,db d)return sqrt((a-c)*(a-c)+(b-d)*(b-d));
bool isp(int x)if(x==1)return false;if(x==2)return true;for(int i=2;i*i<=x;++i)if(x%i==0)return false;return true;
inline int read()
    char ch=getchar();int s=0,w=1;
    while(ch<48||ch>57)if(ch==‘-‘)w=-1;ch=getchar();
    while(ch>=48&&ch<=57)s=(s<<1)+(s<<3)+ch-48;ch=getchar();
    return s*w;

inline void write(int x)
    if(x<0)putchar(‘-‘),x=-x;
    if(x>9)write(x/10);
    putchar(x%10+48);

int gcd(int a, int b)
    if(a==0) return b;
    if(b==0) return a;
    if(!(a&1)&&!(b&1)) return gcd(a>>1,b>>1)<<1;
    else if(!(b&1)) return gcd(a,b>>1);
    else if(!(a&1)) return gcd(a>>1,b);
    else return gcd(abs(a-b),min(a,b));

int lcm(int x,int y)return x*y/gcd(x,y);

int getidx(int i,int j)
    if(i<=3)
    
        if(j<=3)        return 1;
        else if(j<=6)   return 2;
        else            return 3;
    
    else if(i<=6)
    
        if(j<=3)        return 4;
        else if(j<=6)    return 5;
        else            return 6;
    
    else
    
        if(j<=3)        return 7;
        else if(j<=6)   return 8;
        else            return 9;
    


int getval(int i,int j)

    if(i==1||j==1||i==9||j==9)   return 6;
    if(i==2||j==2||i==8||j==8)     return 7;
    if(i==3||j==3||i==7||j==7)   return 8;
    if(i==4||j==4||i==6||j==6)   return 9;
    return 10;


int mp[10][10];
bool hang[10][10],lie[10][10],gong[10][10];
int ans=-1,mem[100][4];
int t=0;

struct node
    int v,id;
    bool operator < (const node& o)constreturn v<o.v;
row[10];

void dfs(int p,int sum)
//    cout<<p<<endl;
    if(p==t)
        ans=max(ans,sum);
        return;
    
    re(i,1,9)
        if(!hang[mem[p][0]][i]&&!lie[mem[p][1]][i]&&!gong[mem[p][3]][i])
            hang[mem[p][0]][i]=lie[mem[p][1]][i]=gong[mem[p][3]][i]=1;
            dfs(p+1,sum+mem[p][2]*i);
            hang[mem[p][0]][i]=lie[mem[p][1]][i]=gong[mem[p][3]][i]=0;
        
    


signed main()
    ios_base::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);
    re(i,1,9) row[i].id=i;
    int now=0;
    re(i,1,9)
        re(j,1,9)
            cin>>mp[i][j];
            if(mp[i][j]==0)
                row[i].v++;
            else
                int k=mp[i][j];
                hang[i][k]=lie[j][k]=gong[getidx(i,j)][k]=1;
                now+=k*getval(i,j);
            
        
    
    sort(row+1,row+10);
    re(i,1,9)
        re(j,1,9)
            if(mp[row[i].id][j]==0)
                mem[t][0]=row[i].id;
                mem[t][1]=j;
                mem[t][2]=getval(row[i].id,j);
                mem[t][3]=getidx(row[i].id,j);
                t++;
            
        
    
    dfs(0,now);
    cout<<ans<<endl;
    return 0;

/*
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
*/