LeetCode 997. Find the Town Judge

Problem Statement

use std::collections::{HashMap, HashSet};

impl Solution {
    pub fn find_judge(n: i32, trust: Vec<Vec<i32>>) -> i32 {
        let mut map: HashMap<i32, HashSet<i32>> = HashMap::new();
        let mut ans = 1;
        for p in trust {
            let (k, v) = (p[0], p[1]);
            map.entry(k).or_insert(HashSet::new());
            map.get_mut(&k).unwrap().insert(v);
        }

        for i in 1..n + 1 {
            if ans == i {
                continue;
            }
            if map.contains_key(&ans) {
                ans = i;
            }
        }

        for i in 1..n + 1 {
            if ans == i {
                continue;
            }

            if map.contains_key(&ans) || map.get(&i).is_none() ||
                !map.get(&i).unwrap().contains(&ans) {
                return -1;
            }
        }

        return ans;
    }
}