LeetCode/rs/time-needed-to-inform-all-employees.rs

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

struct Solution {}
impl Solution {
    fn from_managers(managers: &[i32]) -> HashMap<usize, HashSet<usize>> {
        let mut mapping = HashMap::new();

        for (i, manager) in managers
            .iter()
            .enumerate()
            .filter(|&(_, &manager)| manager != -1)
        {
            mapping
                .entry(*manager as usize)
                .or_insert_with(HashSet::new)
                .insert(i);
        }

        mapping
    }

    pub fn num_of_minutes(_n: i32, head_id: i32, manager: Vec<i32>, inform_time: Vec<i32>) -> i32 {
        let manager_mapping = Solution::from_managers(&manager);

        let mut q = VecDeque::new();
        q.push_back((head_id as usize, 0));

        let mut minutes = -1;
        while let Some((manager, t)) = q.pop_front() {
            minutes = std::cmp::max(minutes, t);

            for employee in manager_mapping.get(&manager).unwrap_or(&HashSet::new()) {
                q.push_back((*employee, t + inform_time[manager]));
            }
        }
        minutes
    }
}

fn main() {}

#[cfg(test)]
mod tests {
    use super::*;

    // Input: n = 1, headID = 0, manager = [-1], informTime = [0]
    // Output: 0
    // Explanation: The head of the company is the only employee in the company.
    #[test]
    fn example_1() {
        assert_eq!(Solution::num_of_minutes(1, 0, vec![-1], vec![0]), 0);
    }

    // Input: n = 6, headID = 2, manager = [2,2,-1,2,2,2], informTime = [0,0,1,0,0,0]
    // Output: 1
    // Explanation: The head of the company with id = 2 is the direct manager of all the employees in the company and needs 1 minute to inform them all.
    // The tree structure of the employees in the company is shown.
    #[test]
    fn example_2() {
        assert_eq!(
            Solution::num_of_minutes(6, 2, vec![2, 2, -1, 2, 2, 2], vec![0, 0, 1, 0, 0, 0]),
            1
        );
    }

    #[test]
    fn regression_1() {
        assert_eq!(
            Solution::num_of_minutes(
                15,
                0,
                vec![-1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6],
                vec![1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0]
            ),
            3
        );
    }
}