UVa 11520 - Fill the Square Solution

#include<iostream>
#include<list>
#include<string>
#include<cstring>
#include<sstream>
#include<cctype>
#include<string.h>
#include<algorithm>
#include<cmath>
#include<stack>
#include<fstream>
#include<cstdlib>
#include<vector>
#include<map>
#include<set>
#include<utility>
#include<iomanip>
#include<queue>

using namespace std;

#define INF (1<<29)
#define SET(a) memset(a,-1,sizeof(a))
#define ALL(a) a.begin(),a.end()
#define CLR(a) memset(a,0,sizeof(a))
#define FILL(a,v) memset(a,v,sizeof(a))
#define PB push_back
#define FOR(i,n) for(int i = 0;i<n;i++)
#define PI acos(-1.0)
#define EPS 1e-9
#define MP(a,b) make_pair(a,b)
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define READ(f) freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
#define LL long long
#define MX 100000
#define MOD 1000000007




int main()
{
    char grid[12][12],c;
    int t,kk=1,n,i,j,k;
    cin>>t;
    while(t--)
    {
        cin>>n;
        cout<<"Case "<<kk++<<":"<<endl;
        for(i=0;i<n;i++)
            for(j=0;j<n;j++)
                cin>>grid[i][j];

        for(i=0;i<n;i++)
        {
            for(j=0;j<n;j++)
            {
                if(grid[i][j]=='.')
                    for(k=65;;k++)
                        {
                           if(grid[i][j-1]!=k && grid[i][j+1]!=k && grid[i-1][j]!=k && grid[i+1][j]!=k)
                           {
                               grid[i][j]=k;
                               break;
                           }
                        }
                cout<<grid[i][j];
            }
            cout<<endl;
        }

        /*for(i=0;i<n;i++)
            for(j=0;j<n;j++)
                grid[i][j]='.';*/
    }

return 0;
}