## 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 `i`

city and the ^{th}`j`

city are directly connected, and ^{th}`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);
}
```

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