HackerEarth Maximum borders problem solution

In this HackerEarth Maximum borders problem solution, you are given a table with n rows and m columns. Each cell is colored white or black. Considering the shapes created by black cells, what is the maximum border of these shapes?

A shape is a set of connected cells. Two cells are connected if they share an edge. Note that no shape has a hole in it.

HackerEarth Maximum borders problem solution.

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

const int maxn = 1e3 + 14;
char c[maxn][maxn];
int main(){
	ios::sync_with_stdio(0), cin.tie(0);
	int t;
	cin >> t;
	while(t--){
		int n, m;
		cin >> n >> m;
		for(int i = 1; i <= n; i++)
			cin >> (c[i] + 1);
		int ans = 0;
		for(int i = 1; i <= n; i++)
			for(int j = 1, ptr = 1; j <= m; j = ptr)
			if(c[i][j] != '#' || c[i - 1][j] == '#')
				ptr++;
			else{
				while(c[i][ptr] == '#' && c[i - 1][ptr] != '#')
					ptr++;
				ans = max(ans, ptr - j);
				}
		for(int i = 1; i <= n; i++)
			for(int j = 1, ptr = 1; j <= m; j = ptr)
			if(c[i][j] != '#' || c[i + 1][ptr] == '#')
					ptr++;
			else{
				while(c[i][ptr] == '#' && c[i + 1][ptr] != '#')
					ptr++;
			ans = max(ans, ptr - j);
			}
		for(int i = 1; i <= m; i++)
			for(int j = 1, ptr = 1; j <= n; j = ptr)
				if(c[j][i] != '#' || c[j][i - 1] == '#')
					ptr++;
				else{
					while(c[ptr][i] == '#' && c[ptr][i - 1] != '#')
						ptr++;
					ans = max(ans, ptr - j);
				}
		for(int i = 1; i <= m; i++)
			for(int j = 1, ptr = 1; j <= n; j = ptr)
		    if(c[j][i] != '#' || c[j][i + 1] == '#')
					ptr++;
				else{
					while(c[ptr][i] == '#' && c[ptr][i + 1] != '#')
						ptr++;
					ans = max(ans, ptr - j);
				}
		cout << ans << '\n';
	}
}