NOIP2009 靶形数独

题目

vijos1755

luogu1074

题解

从右下角开始倒搜，顺搜会被卡，然后。。。就是特别暴力特别暴力的搜。。。

vijos AC，luogu T了一个点，我果然还是比较菜

代码

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;

int n,num,mp[10][10],ans=-1;
bool l[10][10],r[10][10],b[10][10];//l[i][j],r[i][j],b[i][j]分别标记第 i行/i列/i块，数字j是否被用过 
int pri[10][10]=
{
    {0,0,0,0,0,0,0,0,0,0},
    {0,6,6,6,6,6,6,6,6,6},
    {0,6,7,7,7,7,7,7,7,6},
    {0,6,7,8,8,8,8,8,7,6},
    {0,6,7,8,9,9,9,8,7,6},
    {0,6,7,8,9,10,9,8,7,6},
    {0,6,7,8,9,9,9,8,7,6},
    {0,6,7,8,8,8,8,8,7,6},   
    {0,6,7,7,7,7,7,7,7,6},
    {0,6,6,6,6,6,6,6,6,6},
};//分值 
int blo[10][10]=
{
    {0,0,0,0,0,0,0,0,0,0},
    {0,1,1,1,2,2,2,3,3,3},
    {0,1,1,1,2,2,2,3,3,3},
    {0,1,1,1,2,2,2,3,3,3},
    {0,4,4,4,5,5,5,6,6,6},
    {0,4,4,4,5,5,5,6,6,6},
    {0,4,4,4,5,5,5,6,6,6},
    {0,7,7,7,8,8,8,9,9,9},   
    {0,7,7,7,8,8,8,9,9,9},
    {0,7,7,7,8,8,8,9,9,9},
};//九个小块 

int cnt;
void dfs(int x,int y)
{
	if(x==1&&y==0) {ans=max(ans,cnt);return;}
    if(!y) {dfs(x-1,9);return;}
    if(mp[x][y]) {cnt+=pri[x][y]*mp[x][y];dfs(x,y-1);cnt-=pri[x][y]*mp[x][y];return;}
    for(int i=1;i<=9;i++)
    {
        if(l[x][i]||r[y][i]||b[blo[x][y]][i]) continue;
        l[x][i]=r[y][i]=b[blo[x][y]][i]=1;
        cnt+=pri[x][y]*i;
        dfs(x,y-1);
        cnt-=pri[x][y]*i;
        l[x][i]=r[y][i]=b[blo[x][y]][i]=0;
    }
}

int main()
{
	for(int i=1;i<=9;i++)
        for(int j=1;j<=9;j++)
        {
            scanf("%d",&mp[i][j]);
            if(!mp[i][j]) continue;
            l[i][mp[i][j]]=r[j][mp[i][j]]=b[blo[i][j]][mp[i][j]]=1;
        }
    dfs(9,9);
    printf("%d",ans);
    return 0;
}