Navigate in a 2D Array Smoothly

#include<bits/stdc++.h>
using  namespace  std;

#define endl     "\n"
#define ll       long long
#define PI       acos(-1.0)
#define test     cout<<"\n****\n"
#define LCM(a,b) ((a/__gcd(a,b))*b)
#define READ(f)  freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
#define precise  fixed(cout);cout<<setprecision(20)
#define fast     ios_base :: sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)

bool isPrime(int num){

    if(num==1 || num==0){
        return false;
    }

    for(int i=2;i*i<=num;i++){
        if(num%i==0){
            return false;
        }
    }
    return true;
}

#define valid(next_x,next_y) next_x>=0 && next_x<row && next_y>=0 && next_y<column
int fx[]={+1,-1,+0,+0};
int fy[]={+0,+0,+1,-1};                   /*for horizontally and vertically*/

int main(){

    int row,column;
    cin>>row>>column;

    int arr[row][column];

    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){
            cin>>arr[i][j];
        }
    }

    cout<<endl;
    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){

            printf("%2d ",arr[i][j]);
        }
        cout<<endl;
    }

    cout<<endl;

    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){

            if(isPrime(arr[i][j])) {

                for (int k = 0; k < 4; k++) {

                    int next_x = i + fx[k];
                    int next_y = j + fy[k];
                    if (valid(next_x, next_y)) {
                        arr[next_x][next_y] = 0;
                    }
                }

            }
        }
    }

    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){
            printf("%2d ",arr[i][j]);
        }
        cout<<endl;
    }

    return 0;
}

*************************************************************************************
*************************************************************************************

#include<bits/stdc++.h>
using  namespace  std;

#define endl     "\n"
#define ll       long long
#define PI       acos(-1.0)
#define test     cout<<"\n****\n"
#define LCM(a,b) ((a/__gcd(a,b))*b)
#define READ(f)  freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
#define precise  fixed(cout);cout<<setprecision(20)
#define fast     ios_base :: sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)

bool isPrime(int num){

    if(num==1 || num==0){
        return false;
    }

    for(int i=2;i*i<=num;i++){
        if(num%i==0){
            return false;
        }
    }
    return true;
}

#define valid(next_x,next_y) next_x>=0 && next_x<row && next_y>=0 && next_y<column
int fx[]={+1,-1,+0,+0,-1,+1,-1,+1};
int fy[]={+0,+0,+1,-1,+1,+1,-1,-1};            /* for horizontally,vertically and diagonally*/

int main(){

    int row,column;
    cin>>row>>column;

    int arr[row][column];

    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){
            cin>>arr[i][j];
        }
    }

    cout<<endl;
    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){

            printf("%2d ",arr[i][j]);
        }
        cout<<endl;
    }

    cout<<endl;

    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){

            if(isPrime(arr[i][j])) {

                for (int k = 0; k < 8; k++) {

                    int next_x = i + fx[k];
                    int next_y = j + fy[k];
                    if (valid(next_x, next_y)) {
                        arr[next_x][next_y] = 0;
                    }
                }

            }
        }
    }

    for(int i=0;i<row;i++){
        for(int j=0;j<column;j++){
            printf("%2d ",arr[i][j]);
        }
        cout<<endl;
    }

    return 0;
}