547. Number of Provinces

There are n cities. Some of them are connected, while some are not. If city a is connected directly with city b, and city b is connected directly with city c, then city a is connected indirectly with city c.

A province is a group of directly or indirectly connected cities and no other cities outside of the group.

You are given an n x n matrix isConnected where isConnected[i][j] = 1 if the ith city and the jth city are directly connected, and isConnected[i][j] = 0 otherwise.

Return the total number of provinces.

 

Example 1:

Input: isConnected = [[1,1,0],[1,1,0],[0,0,1]]
Output: 2

Example 2:

Input: isConnected = [[1,0,0],[0,1,0],[0,0,1]]
Output: 3

 

Constraints:

• 1 <= n <= 200
• n == isConnected.length
• n == isConnected[i].length
• isConnected[i][j] is 1 or 0.
• isConnected[i][i] == 1
• isConnected[i][j] == isConnected[j][i]

Rust Solution

struct Solution;

impl Solution {
    fn dfs(m: &mut Vec<Vec<i32>>, visited: &mut Vec<bool>, i: usize, n: usize) {
        for j in 0..n {
            if m[i][j] == 1 && !visited[j] {
                visited[j] = true;
                Self::dfs(m, visited, j, n);
            }
        }
    }

    fn find_circle_num(mut m: Vec<Vec<i32>>) -> i32 {
        let mut res = 0;
        let n = m.len();
        let mut visited: Vec<bool> = vec![false; n];
        for i in 0..n {
            if !visited[i] {
                visited[i] = true;
                Self::dfs(&mut m, &mut visited, i, n);
                res += 1;
            }
        }
        res
    }
}

#[test]
fn test() {
    let m: Vec<Vec<i32>> = vec_vec_i32![[1, 1, 0], [1, 1, 0], [0, 0, 1]];
    assert_eq!(Solution::find_circle_num(m), 2);
    let m: Vec<Vec<i32>> = vec_vec_i32![[1, 1, 0], [1, 1, 1], [0, 1, 1]];
    assert_eq!(Solution::find_circle_num(m), 1);
}