https://www.acmicpc.net/problem/13023
깊이가 5 이상인 그래프
를 찾는 문제였다시간 복잡도는 O(V * (V+E)) = O(V^2)이다.(V, E 범위가 2000이므로 충분)
import sys
input = lambda : sys.stdin.readline().rstrip()
def dfs(x,cnt): #O(V+E)
if cnt == GOAL:
print(1)
exit()
for u in graph[x]:
if not visited[u]:
visited[u] = True
dfs(u,cnt+1)
visited[u] = False
if __name__ == '__main__':
v, e = map(int, input().split())
graph = [[] for _ in range(v)]
GOAL = 5
visited = [False] * v
for _ in range(e):
x, y = map(int, input().split())
graph[x].append(y)
graph[y].append(x)
for i in range(v): # O(V)
visited[i] = True
dfs(i,1)
visited[i] = False
print(0)