fn main() {
    println!("Hello, world!");
}

struct Solution;

impl Solution {
    pub fn num_equiv_domino_pairs(dominoes: Vec<Vec<i32>>) -> i32 {
        let mut map = [0;100];
        for d in dominoes {
            if let [i,j] = d[..] {
                map[(i.max(j) * 10 + i.min(j)) as usize] += 1;
            }
        }
        map.iter().filter(|&&x| x > 1).map(|&x| (x *(x-1))/2).sum::<i32>()
    }
}