PrintingPatterns_Hackerearth

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

int dx[8]={1,1,0,-1,-1,-1,0,1}; //direction vectors
int dy[8]={0,1,1,1,0,-1,-1,-1}; //direction vectors
int r,c,cx,cy;

bool valid(int cx,int cy)
{
    if(cx<0 || cx>=r || cy<0 || cy>=c)
        return false;
    return true;
}

main()
{
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    cin>>r>>c>>cx>>cy;
    int val=0;

    vector<vector<int>>mat(r,vector<int>(c));
    vector<vector<bool>>vis(r,vector<bool>(c,false));

    queue<pair<int,int>>q;
    int x,y,sz;pair<int,int>p;
    mat[cx][cy]=val;
    vis[cx][cy]=true;
    q.push({cx,cy});
    sz=1;val++;

    while(!q.empty())
    {
        p=q.front();
        x=p.first;y=p.second;
        q.pop();sz--;

        for(int i=0;i<8;i++){
            if(valid(x+dx[i],y+dy[i]) && !vis[x+dx[i]][y+dy[i]]){
                q.push({x+dx[i],y+dy[i]});
                vis[x+dx[i]][y+dy[i]]=true;
                mat[x+dx[i]][y+dy[i]]=val;
            }
        }
        if(sz==0){
            val++;
            sz=q.size();
        }
    }


    for(int i=0;i<r;i++){
        for(int j=0;j<c;j++){
            cout<<mat[i][j]<<' ';
        }
        cout<<endl;
    }

    return 0;
}