对集合一等支持而且支持闭包的语言用来描述图很方便
g_text = """
{
0:[6,2,1,5],
1:[0],
2:[0],
3:[5,4],
4:[5,6,3],
5:[3,4,0],
6:[0,4],
7:[8],
9:[11,10,12],
10:[9],
11:[9,12],
12:[9,11],
}
"""
## 深度优先
def dfs(g,n):
visited =set()
where_from = dict()
def __dfs(n):
visited.add(n)
for x in g.get(n,[]):
if x not in visited:
where_from[x]=n
__dfs(x)
__dfs(n)
return where_from
## 广度优先
def bfs(g,n):
visited = set()
where_from = dict()
queue = []
queue.append(n)
while queue:
head = queue.pop(0)
visited.add(head)
for x in g.get(head,[]):
if x not in visited:
where_from[x] = head
queue.append(x)
return where_from
## 获得路径
def get_path(where_from,_from,to):
try:
path = []
x = to
while x != _from:
path.insert(0,x)
x = where_from[x]
path.insert(0,x)
return path
except:
return []
## 连通部分计数
def connected_component(g):
visited = set()
cc = dict()
where_from = dict()
count = 0
def __dfs(n):
visited.add(n)
cc[n] = count
for x in g.get(n,[]):
if x not in visited:
where_from[x] = n
__dfs(x)
for x in g:
if x not in visited:
count += 1
__dfs(x)
return cc
## 判断环路
def has_cycle(g):
cycle = []
visited = set()
where_from = dict()
def dfs(u,v):
visited.add(u)
for x in g.get(u,[]):
if x not in visited:
where_from[x]=u
dfs(x,u)
elif x!=v :
path = get_path(where_from,x,u)
if path:
cycle.append(path+[x])
for x in g:
if x not in visited:
dfs(x,x)
return cycle
## 两色
def two_color(g):
color = dict()
visited = set()
two_color_able =True
def dfs(n):
visited.add(n)
for x in g.get(n,[]):
if x not in visited:
color[x] = not color[n]
dfs(x)
elif color[x] == color[n]:
two_color_able = False
for x in g:
if x not in visited:
color[x] = True
dfs(x)
return two_color_able,color
if __name__ == "__main__":
g = eval(g_text)
print(two_color(g))
