deus-nqueens 0.4.2

const N: usize = 8;

fn try1(mut board: &mut [[bool; N]; N], row: usize, mut count: &mut i64) {
    if row == N {
        *count += 1;
        for r in board.iter() {
            println!("{}", r.iter().map(|&x| if x {"x"} else {"."}.to_string()).collect::<Vec<String>>().join(" "))
        }
        println!("");
        return
    }
    for i in 0..N {
        let mut ok: bool = true;
        for j in 0..row {
            if board[j][i]
                || i+j >= row && board[j][i+j-row]
                || i+row < N+j && board[j][i+row-j]
            { ok = false }
        }
        if ok {
            board[row][i] = true;
            try1(&mut board, row+1, &mut count);
            board[row][i] = false;
        }
    }
}

#[test]
fn main() {
    let mut board: [[bool; N]; N] = [[false; N]; N];
    let mut count: i64 = 0;
    try1(&mut board, 0, &mut count);
    println!("Found {} solutions", count)
}