CodeChef submission 128753 (C++ 4.0.0-8) plaintext list. Status: AC, problem J1, contest NOV09. By Awake (Awake), 2009-11-10 02:45:38.
#include<stdio.h>
#include<iostream>
using namespace std;
 
int grid[9][9];
int rowinfo[9],colinfo[9],diaginfo[2],subgrid[9];
int inxb[81],counter,nob;
int SudokuSolver(){
	if(counter==nob)return 1;
	int i,x,y,num,boolent,choice,minchoice=10,tx,ty,tnum,z,ix;
	for(i=counter;i<nob;i++){
		choice=9;
		tx=inxb[i]/9;
		ty=inxb[i]%9;
		tnum=rowinfo[tx] | colinfo[ty] | subgrid[3*(tx/3)+ty/3];
		if(tx==ty)tnum|=diaginfo[0];
		if(tx==8-ty)tnum|=diaginfo[1];
		z=tnum;
		z=z>>1;//we are dealing with 9 bits before the last bit
		while(z){
			choice-=(z&1);
			z=z>>1;
		}
		if(choice<minchoice){
			minchoice=choice;
			x=tx;y=ty;num=tnum;
			ix=i;
		}
	}
	swap(inxb[counter],inxb[ix]);
	bool d1=(x==y),d2=(x==8-y);
//	num=num>>1;
//	cout<<x<<y<<endl;
//	cout<<num<<endl;
	for(i=1;i<10;i++){
		boolent=1<<i;
		//cout<<(num&boolent)<<endl;
		if((num&boolent)==0){
			//cout<<"hi"<<endl;
			grid[x][y]=i;
			rowinfo[x]=rowinfo[x] | boolent;
			colinfo[y]=colinfo[y] | boolent;
			subgrid[3*(x/3)+y/3]|=boolent;
			if(d1)diaginfo[0]|=boolent;
			if(d2)diaginfo[1]|=boolent;
			counter++;
			if(SudokuSolver())
				return 1;
			counter--;
			rowinfo[x]=rowinfo[x]^boolent;
			colinfo[y]=colinfo[y]^boolent;
			subgrid[3*(x/3)+y/3]^=boolent;
			if(d1)diaginfo[0]^=boolent;
			if(d2)diaginfo[1]^=boolent;
 
		}
	}
	return 0;
}
int main(){
	int t;
	scanf("%d",&t);
	while(t--){
		getchar();
		int i,j,ent,a,b,boolent;
		char ch,in[10];
		nob=0;
		diaginfo[0]=diaginfo[1]=0;
		for(i=0;i<9;i++)
			rowinfo[i]=colinfo[i]=subgrid[i]=0;
		for(i=0;i<9;i++){
			scanf("%s",in);
			for(j=0;j<9;j++){
				if(in[j]=='.'){
					grid[i][j]=0;
					inxb[nob++]=i*9+j;
				}
				else {
					ent=in[j]-48;
					grid[i][j]=ent;
					boolent=1<<ent;
					rowinfo[i]=rowinfo[i] | boolent;
					colinfo[j]=colinfo[j] | boolent;
					subgrid[3*(i/3)+j/3]|=boolent;
					if(i==j)diaginfo[0]|=boolent;
					if(i==8-j)diaginfo[1]|=boolent;
				}
 
			}
		}
		//no of choices
		int choice[81];
		/*for(i=0;i<nob;i++){
			choice[i]=9;
			int x=inxb[i]/9,y=inxb[i]%9,num;
			num=rowinfo[x] | colinfo[y] | subgrid[3*(x/3)+y/3];
			if(x==y)num|=diaginfo[0];
			if(x==8-y)num|=diaginfo[1];
			num=num>>1;//we are dealing with 9 bits before the last bit
			while(num){
				choice[i]-=(num&1);
				num=num>>1;
			}
		}*/
		//sort inxb
		/*for(i=0;i<nob-1;i++){
			for(j=0;j<nob-i-1;j++){
				if(choice[j]>choice[j+1]){
					swap(inxb[j],inxb[j+1]);
					swap(choice[j],choice[j+1]);
				}
			}
		}*/
		getchar();
		counter=0;
		SudokuSolver();
		//	cout<<"Solved !!\n";
		for(i=0;i<9;i++){
			for(j=0;j<9;j++)
				printf("%d",grid[i][j]);
			printf("\n");
		}
		printf("\n");
 
	}
}