use std::collections::VecDeque;

struct Solution {}
impl Solution {
    fn bfs(graph: &[Vec<i32>], visited: &mut [bool], u0: usize) {
        let mut q = VecDeque::new();
        q.push_back(u0);
        visited[u0] = true;

        while let Some(u) = q.pop_front() {
            for v in (0..graph.len()).filter(|&v| graph[u][v] != 0) {
                if visited[v] {
                    continue;
                }

                q.push_back(v);
                visited[v] = true;
            }
        }
    }

    pub fn find_circle_num(is_connected: Vec<Vec<i32>>) -> i32 {
        let mut visited = vec![false; is_connected.len()];

        let mut count = 0;
        for i in 0..is_connected.len() {
            if visited[i] {
                continue;
            }

            Solution::bfs(&is_connected, &mut visited, i);
            count += 1;
        }

        count
    }
}

fn main() {}

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

    // Input: isConnected = [[1,1,0],[1,1,0],[0,0,1]]
    // Output: 2
    #[test]
    fn example_1() {
        assert_eq!(
            Solution::find_circle_num(vec![vec![1, 1, 0], vec![1, 1, 0], vec![0, 0, 1]]),
            2
        );
    }

    // Input: isConnected = [[1,0,0],[0,1,0],[0,0,1]]
    // Output: 3
    #[test]
    fn example_2() {
        assert_eq!(
            Solution::find_circle_num(vec![vec![1, 0, 0], vec![0, 1, 0], vec![0, 0, 1]]),
            3
        );
    }
}