Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	scanner.Split(bufio.ScanWords)
	scanner.Scan()
	table := [9][9]int{}
	check := [9][9]bool{}
	n, _ := strconv.Atoi(scanner.Text())
	for n > 0 {
		n--
		for i := 0; i < 9; i++ {
			for j := 0; j < 9; j++ {
				table[i][j] = nextInt()
			}
		}
		for i := 0; i < 9; i++ {
			for j := 0; j < 9; j++ {
				ok := true
				for k := 0; k < 9; k++ {
					if table[i][j] == table[i][k] && j != k {
						ok = false
					}
				}
				for k := 0; k < 9; k++ {
					if table[i][j] == table[k][j] && i != k {
						ok = false
					}
				}
				seci := i / 3
				secj := j / 3
				for k := 0; k < 3; k++ {
					for l := 0; l > 3; l++ {
						if table[seci*3+k][secj*3+l] == table[i][j] && seci*3+k != i && secj*3+l != j {
							ok = false
						}
					}
				}
				if !ok {
					check[i][j] = true
				}
			}
		}
		for i := 0; i < 9; i++ {
			for j := 0; j < 9; j++ {
				if check[i][j] {
					fmt.Print("*")
				} else {
					fmt.Print(" ")
				}
				fmt.Print(table[i][j])
			}
			fmt.Println()
		}
		if n != 0 {
			fmt.Println()
		}
	}
}

func nextInt() int {
	scanner.Scan()
	i, e := strconv.Atoi(scanner.Text())
	if e != nil {
		panic(e)
	}
	return i
}

C++: #define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <cmath>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<int> vi;
typedef vector<vi> vvi;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(int i=a; i<int(b); i++)
#define rep(i,b) loop(i,0,b)
#define each(e,c) for(auto& e:c)
#define iter(it,c) for(auto it=c.begin(); it!=c.end(); ++it)

ll const inf = 1<<28;
double const pi = acos(-1);

int g[9][9];
bool ok[9][9];

void solve(){
    rep(y,9)rep(x,9){
        loop(i,y+1,9){
            if(g[y][x]==g[i][x]){
                ok[i][x]=false;
                ok[y][x]=false;
            }
        }

        loop(j,x+1,9){
            if(g[y][x]==g[y][j]){
                ok[y][j]=false;
                ok[y][x]=false;
            }
        }
    }

    rep(i,3)rep(j,3){
        rep(a,9){
            int x=a%3+i*3;
            int y=a/3+j*3;
            loop(b,a+1,9){
                int xx=b%3+i*3;
                int yy=b/3+j*3;
                if(g[y][x]==g[yy][xx]){
                    ok[yy][xx]=false;
                    ok[y][x]=false;
                }
            }
        }
    }

}

int main(){
    int n;
    cin>>n;
    rep(i,n){
        rep(y,9)rep(x,9){
            ok[y][x]=true;
        }
        rep(y,9)rep(x,9)cin>>g[y][x];
        solve();
        rep(y,9)rep(x,9){
            printf("%c%d",ok[y][x]?' ':'*',g[y][x]);
            if(x+1==9)puts("");
        }
        if(i+1!=n)puts("");
    }
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;

int main(){

	int n, l[10][10], a[10][10];
	int m[10][10] = {0};

	cin >> n;
	
	for(int i=0; i<n; i++){
		for(int j=1; j<10; j++){
			for(int k=1; k<10; k++){
				l[j][k] = 0;
				a[j][k] = 0;
			}
		}
//		fill(l, l+9*9, 0);
//		fill(a, a+9*9, 0);

		for(int j=1; j<10; j++){
			for(int k=1; k<10; k++){
				scanf("%d", &m[j][k]);
				l[j][m[j][k]]++;
				a[k][m[j][k]]++;
			}
		}

		for(int j=1; j<10; j++){
			for(int k=1; k<10; k++){
				if(l[j][m[j][k]] == 1 && a[k][m[j][k]] == 1){
					cout << " ";
				}
				else{
					cout << "*";
				}
				cout << m[j][k];
			}
			cout << endl;
		}
		cout << endl;
	}

	return 0;

}

C++: #include<iostream>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<map>
#include<cstdio>
#include<cmath>
#define pb push_back
#define mp make_pair
#define loop(i,a,b) for(int i=a;i<b;i++)
#define rep(i,b) loop(i,0,b)
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
using namespace std;
int main(){
	int n;
	cin>>n;
	bool h=false;
	rep(w,n){
	if(h)cout<<endl;
		int in[9][9]={0};
		rep(j,9)rep(k,9)cin>>in[j][k];
		int out[9][9]={0};
		rep(i,9){
			rep(j,9){
				int co=0;
				rep(k,9)if(in[i][k]==j+1)co++;
				if(co>1)rep(k,9)if(in[i][k]==j+1)out[i][k]=1;
			}
		}
		rep(i,9){
			rep(j,9){
				int co=0;
				rep(k,9)if(in[k][i]==j+1)co++;
				if(co>1)rep(k,9)if(in[k][i]==j+1)out[k][i]=1;
			}
		}
		rep(i,3)rep(j,3){
			map<int,int>m;
			rep(a,3)rep(b,3)m[in[3*i+a][3*j+b]]++;
			rep(k,9)if(m[k]>=2)rep(a,3)rep(b,3)if(in[3*i+a][3*j+b]==k)out[3*i+a][3*j+b]=1;
		}
		rep(i,9){
			rep(j,9)
				if(out[i][j]==0)cout<<" "<<in[i][j];
				else cout<<"*"<<in[i][j];
			cout<<endl;
		}
		h=true;
	}
}

C++: #include<cstdio>
#include<cmath>
#include<algorithm>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<cstdlib>
#include<iomanip>
#include<queue>
#include<set>
#include <valarray>
#include<stack>

using namespace std;

int board[9][9];

bool Solution(int x, int y)
{
    int count = 0;
    
    for (int i = 0; i < 9; i++)
    {
        if (board[x][i] == board[x][y])
        {
            count++;
        }
        
        if (board[i][y] == board[x][y])
        {
            count++;
        }
    }
    
    int devideX = x / 3;
    int devideY = y / 3;
    
    for (int i = 0; i < 3; i++)
    {
        for (int j = 0; j < 3; j++)
        {
            if (board[devideX * 3 + i][devideY * 3 + j] == board[x][y])
            {
                count++;
            }
        }
    }
    
    return count == 3;
}

int main()
{
    int n;
 
    bool flag = true;
    
    cin>>n;
    
    while(n--)
    {
        if (flag)
        {
            flag = false;
        }
        else
        {
            cout << endl;
        }
        
        for (int j = 0; j < 9; j++)
        {
            for (int k = 0; k < 9; k++)
            {
                cin>>board[j][k];
            }
        }
        
        for (int j = 0; j < 9; j++)
        {
            for (int k = 0; k < 9; k++)
            {
                char c = ' ';
                
                if (!Solution(j, k))
                {
                    c = '*';
                }
                
                cout << c << board[j][k];
            }
            
            cout << endl;
        }
    }
    
    return 0;
}

C++: #include<stdio.h>
#include <string.h>

int main(void){
	int n,i,j,k=0;
	int joudan[5],gedan[5];
	int data[7][5];

	while(1){
		
		if(scanf("%d",&n)==EOF)break;
		for(i=0;i<7;i++)
			for(j=0;j<5;j++)
				data[i][j]=1;

		for(i=4;i>=0;i--){
			joudan[i]=(n%10)/5;
			gedan[i]=(n%10)%5;
			n/=10;
		}
		  for(i=0;i<5;i++){//上段の判定
			  if(joudan[i]==1)
				  data[0][i]=0;
			  else 
				  data[1][i]=0;
		  }

		 for(i=0;i<5;i++){//下段の判定
			  if(gedan[i]==0)
				 data[2][i]=0;
			  else if(gedan[i]==1)
				  data[3][i]=0;
			  else if(gedan[i]==2)
				  data[4][i]=0;
			  else if(gedan[i]==3)
				  data[5][i]=0;
			  else if(gedan[i]==4)
				  data[6][i]=0;
		  }
		for(i=0;i<2;i++)
			for(j=0;j<5;j++){
				if(data[i][j]==1)
					printf("*");
				else
					printf(" ");
				if(j==4) printf("\n");
			}

		for(i=0;i<5;i++){
			printf("=");
			if(i==4) printf("\n");
		}

		for(i=2;i<7;i++)
			for(j=0;j<5;j++){
				if(data[i][j]==1)
					printf("*");
				else
					printf(" ");
				if(j==4&&i!=6) printf("\n");
			}
			puts("");
	}
	return 0;
}