I would like to thank everyone who contributed to the creation and operation of this amazing website. But I couldn't find any way to use dark theme here. So I am curious to learn how can I do this ? and why isn't there a button somewhere to do that?

This massive amount of light from the screen is absolutely devastating to my mood and focus. Any one has the same issue? Any way to change it to dark mode?

What doe the following code mean ? Why use it ?

#ifdef _DEBUG
	freopen("input.txt", "r", stdin);
//	freopen("output.txt", "w", stdout);
#endif

bool dfs(int r, int c) {
    if (r > n || c > m || vis[ndx(r, c)] || grid[ndx(r,c)] == '#') return false;
    if (r == n && c == m) return true;
    if (r!=1 || c!=1) vis[ndx(r, c)] = true;
    return dfs(r+1, c) || dfs(r, c+1);
}

Why Does the previous code terminate once a call is evaluated as true ?

In other words, Why it doesn't mark each reachable cell that does not have "#", as expected ?

How can I find all Div 3 contests ?

When I choose Clang++17 Diagnostics and submit this solution, The verdict is TLE. But

when I choose any GNU G++ and submit the exact same code, It's Accepted.

why ?