BFS (breadth first search)

루트노드와 같은 거리에 있는 노드 우선

Queue 사용

graph_list = {1: set([3, 4]),
              2: set([3, 4, 5]),
              3: set([1, 5]),
              4: set([1]),
              5: set([2, 6]),
              6: set([3, 5])}
root_node = 1

from collections import deque

def BFS_with_adj_list(graph, root):
    visited = []
    queue = deque([root])

    while queue:
        n = queue.popleft()
        if n not in visited:
            visited.append(n)
            queue += graph[n] - set(visited)
    return visited
  
print(BFS_with_adj_list(graph_list, root_node))

DFS (depth first search)

Stack 사용

def DFS_with_adj_list(graph, root):
    visited = []
    stack = [root]

    while stack:
        n = stack.pop()
        if n not in visited:
            visited.append(n)
            stack += graph[n] - set(visited)
    return visited

print(BFS_with_adj_list(graph_list, root_node))