Graph

DFS

def dfs(**args):
	if (...): # ending condition
		# save results
		return
				
	for (...): # select adjacent nodes of this node
		# handle node
		dfs(...) # recursion
		# cancel operation

BFS

def bfs(**args):
	queue = dequeue(start)
	res = []
	while queue:
		for _ in range(len(queue)):
			cur = queue.popleft()
			res.append(cur)
			for c in cur.children:
				if c:
					queue.append(c)

• 200: Number of Islands