题目
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]
is1
or0
.isConnected[i][i] == 1
isConnected[i][j] == isConnected[j][i]
思路
dfs搜索一座城市关联的所有城市,并标记已搜过。
并查集,待研究。
代码
python版本:
class Solution:
def findCircleNum(self, isConnected: List[List[int]]) -> int:
def fill(i):
if isConnected[i][i] == 0:
return
isConnected[i][i] = 0
for j in range(len(isConnected[i])):
if isConnected[i][j]:
fill(j)
cnt = 0
for i in range(len(isConnected)):
if isConnected[i][i]:
cnt += 1
fill(i)
return cnt