백준 11724번 - 연결 요소의 개수

from collections import deque
import sys

# 입력
n, m = map(int,sys.stdin.readline().split())
graph = dict()
visited = [False] * (n+1)
count = 0
for _ in range(m):
  u, v = map(int,sys.stdin.readline().split())
  if u in graph:
    graph[u].append(v)
  else:
    graph[u] = [v]
  if v in graph:
    graph[v].append(u)
  else:
    graph[v] = [u]
    
# 처리
def dfs(graph, queue):
  while queue:
    c = int(queue.pop())
    if visited[c] == False:
      visited[c] = True
      if c in graph:
        queue += deque(graph[c])

for i in range(1, n+1):
  if visited[i] == False:
    dfs(graph, deque([i]))
    count += 1

print(count)