Number of provinces

class Solution:
    def findCircleNum(self, isConnected: List[List[int]]) -> int:
        cities = len(isConnected)
        visited = set()
        res = 0
        for i in range(cities):
            if i not in visited:
                Q = deque([i])
                while Q:
                    c = Q.popleft()
                    for j in range(cities):
                        if isConnected[c][j] == 1 and j not in visited:
                            visited.add(j)
                            Q.append(j)
                res += 1
        return res

Number of Provinces

Difficulty: Medium

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]