建议使用该AC题解

#include <bits/stdc++.h>
using namespace std;
int num,ans=-1,cur;
int G[10][10],rec[512],power[512];
int row[10],col[10],grid[10];
const int grade[9][9]={
{6,6,6,6,6,6,6,6,6},
{6,7,7,7,7,7,7,7,6},
{6,7,8,8,8,8,8,7,6},
{6,7,8,9,9,9,8,7,6},
{6,7,8,9,10,9,8,7,6},
{6,7,8,9,9,9,8,7,6},
{6,7,8,8,8,8,8,7,6},
{6,7,7,7,7,7,7,7,6},
{6,6,6,6,6,6,6,6,6}
};
int g(int x,int y) {
    return x/3*3+y/3;
}
void flip(int x,int y,int val) {
    row[x]^=1<<(val-1);
    col[y]^=1<<(val-1);
    grid[g(x,y)]^=1<<(val-1);
}
void dfs(int now,int sum) {
    if(sum+now*9*10<=ans) return;
    if(now==0) {
        ans=max(ans,sum);
        return;
    }
    int minn=10,x,y;
    for(int i=0;i<9;i++) {
        for(int j=0;j<9;j++) {
            if(G[i][j]) continue;
            int val=row[i]&col[j]&grid[g(i,j)];
            if(rec[val]<minn) minn=rec[val],x=i,y=j;
        }
    }
    int val=row[x]&col[y]&grid[g(x,y)];
    for(;val;val-=val&-val) {
        int k=power[val&-val];
        G[x][y]=k;
        flip(x,y,k);
        dfs(now-1,sum+k*grade[x][y]);
        G[x][y]=0;
        flip(x,y,k);
    }
}
int main() {
    for(int i=1;i<1<<9;i++)
        for(int j=i;j;j-=j&-j)
            rec[i]++;
    for(int i=0;i<9;i++) {
        row[i]=col[i]=grid[i]=(1<<9)-1;
        power[1<<i]=i+1;
    }
    for(int i=0;i<9;i++) {
        for(int j=0;j<9;j++) {
            scanf("%d",&G[i][j]);
            if(G[i][j]==0) num++;
            else flip(i,j,G[i][j]),cur+=grade[i][j]*G[i][j];
        }
    }
    dfs(num,cur);
    printf("%d\n",ans);
    return 0;
}

C++ :

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
using namespace std;
bool h[9][9],l[9][9],q[10][9];
int s[9][9];
struct C{
	int no;
	int num;
}c[9];
int ans = 0;
bool cmp(C a,C b){
	return a.num < b.num; 
}
int count(int x, int y){
	if(x==4&&y==4)
		return 10;
	else if(x>=3&&x<=5&&y>=3&&y<=5)
		return 9;
	else if(x>=2&&x<=6&&y>=2&&y<=6)
		return 8;
	else if(x>=1&&x<=7&&y>=1&&y<=7)
		return 7;
	else if(x>=0&&x<=8&&y>=0&&y<=8)
		return 6;
}
int space(int x,int y) {
	if(x>=0&&x<3&&y>=0&&y<3)
		return 1;
	if(x>=0&&x<3&&y>=3&&y<6)
		return 2;
	if(x>=0&&x<3&&y>=6&&y<9)
		return 3;
	if(x>=3&&x<6&&y>=0&&y<3)
		return 4;
	if(x>=3&&x<6&&y>=3&&y<6)
		return 5;
	if(x>=3&&x<6&&y>=6&&y<9)
		return 6;
	if(x>=6&&x<9&&y>=0&&y<3)
		return 7;
	if(x>=6&&x<9&&y>=3&&y<6)
		return 8;
	if(x>=6&&x<9&&y>=6&&y<9)
		return 9;

}
int tot(){
	int sum = 0;
	for(int i=0;i<9;i++)
		for(int j=0;j<9;j++){
			sum += s[i][j]*count(i,j);
		}
	return sum ; 
}
void dfs(int x,int y) {
	int xx = c[x].no;
	if(s[xx][y]!=0) {
		if(x==8&&y==8) {
			int sum = tot();
			if(sum>ans)
				ans = sum;
			return ;
		}
		if(y==8)
			dfs(x+1,0);
		else
			dfs(x,y+1);
	} else {
		for(int i=1; i<=9; i++) {
			if(!h[xx][i]&&!l[y][i]&&!q[space(xx,y)][i]) {
				s[xx][y] = i;
				h[xx][i] = 1;
				l[y][i] = 1;
				q[space(xx,y)][i] = 1;
				dfs(x,y);
				s[xx][y] = 0;
				h[xx][i] = 0;
				l[y][i] = 0;
				q[space(xx,y)][i] = 0;
			}

		}
	}


}
int main() {
	int points = 0;
	for(int i=0; i<9; i++)
		for(int j=0; j<9; j++) {
			cin>>s[i][j];
			if(s[i][j]!=0) {
				
				h[i][s[i][j]] = 1;
				l[j][s[i][j]] = 1;
				q[space(i,j)][s[i][j]] = 1;
			}
			else{
				c[i].num++ ;
				c[i].no = i;
			}
		}
	sort(c,c+9,cmp);
	dfs(0,0);
	if(ans)
		cout<<ans<<endl;
	else 
		cout<<-1<<endl;
	return 0;
}