LeetCode 982. Triples with Bitwise AND Equal To Zero

Problem Statement

use std::collections::HashMap;

impl Solution {
    pub fn count_triplets(a: Vec<i32>) -> i32 {
        let mut map = HashMap::new();
        let mut ans = 0;
        for i in 0..a.len() {
            for j in 0..a.len() {
                let val = map.entry(a[i] & a[j]).or_insert(0);
                *val += 1;
            }
        }

        for i in a {
            for (key, val) in &map {
                if key & i == 0 {
                    ans += *val;
                }
            }
        }
        return ans;
    }
}