11724) 연결 요소의 개수 (DFS).py

import sys
from collections import deque
sys.setrecursionlimit(10**8)

def dfs(n):
    if visited[n]: return
    visited[n] = True
    for node in graph[n]:
        dfs(node)

def dfscheck():
    cnt = 0
    for i in range(1,len(graph)):
        if not visited[i]:
            cnt+=1
            dfs(i)
    return cnt

V, E = map(int, sys.stdin.readline().split())
graph = [[] for x in range(V+1)]
visited = [False for x in range(V+1)]

for i in range(1,E+1):
    n1, n2 = map(int, sys.stdin.readline().split())
    graph[n1].append(n2)
    graph[n2].append(n1)

for nodes in graph:
    nodes.sort()

res = dfscheck()
print(res)