使用这里提出的python配方：
http://code.activestate.com/recipes/119466-dijkstras-algorithm-for-shortest-paths/
和
http://code.activestate.com/recipes/117228-priority-dictionary/
并使用以下图表作为输入：
(function () {
'use strict';
// This is the array the isAircraftDueForTireChange function expects.
// Assume the following object was loaded via an API as JSON.
// This object may contain some unrealistic or duplicate data; It is only intended for testing.
window.CAMP = {
aircraftData: [
{
// Should require maintenance
id: 1,
lastTireChange: new Date('9/1/2016'),
manufacturer: 'FooPlane',
landings: [
new Date('9/1/2015'),
new Date('9/5/2015'),
new Date('9/12/2016'),
new Date('9/12/2015'),
new Date('1/1/2016'),
new Date('10/1/2015'),
new Date('10/23/2015'),
new Date('9/12/2016'),
new Date('10/28/2015'),
new Date('11/15/2015'),
new Date('12/22/2015'),
new Date('12/22/2015'),
new Date('12/27/2015'),
new Date('1/7/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/1/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/23/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/3/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016')
]
},
{
// Should not require maintenance
id: 2,
lastTireChange: new Date('10/29/2016'),
manufacturer: 'FooPlane',
landings: [
new Date('9/1/2015'),
new Date('9/5/2015'),
new Date('9/12/2016'),
new Date('9/12/2015'),
new Date('1/1/2016'),
new Date('10/1/2015'),
new Date('10/23/2015'),
new Date('9/12/2016'),
new Date('10/28/2015'),
new Date('11/15/2015'),
new Date('12/22/2015'),
new Date('12/22/2015'),
new Date('12/27/2015'),
new Date('1/7/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/1/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/23/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/3/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016')
]
},
{
// Should require maintenance
id: 3,
lastTireChange: new Date('9/1/2016'),
manufacturer: 'BarPlane',
landings: [
new Date('9/1/2015'),
new Date('9/5/2015'),
new Date('9/12/2016'),
new Date('9/12/2015'),
new Date('1/1/2016'),
new Date('10/1/2015'),
new Date('10/23/2015'),
new Date('9/12/2016'),
new Date('10/28/2015'),
new Date('11/15/2015'),
new Date('12/22/2015'),
new Date('12/22/2015'),
new Date('12/27/2015'),
new Date('1/7/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/1/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/23/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/3/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016')
]
},
{
// Should not require maintenance
id: 4,
lastTireChange: new Date('10/29/2016'),
manufacturer: 'BarPlane',
landings: [
new Date('9/1/2015'),
new Date('9/5/2015'),
new Date('9/12/2016'),
new Date('9/12/2015'),
new Date('1/1/2016'),
new Date('10/1/2015'),
new Date('10/23/2015'),
new Date('9/12/2016'),
new Date('10/28/2015'),
new Date('11/15/2015'),
new Date('12/22/2015'),
new Date('12/22/2015'),
new Date('12/27/2015'),
new Date('1/7/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('2/1/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/1/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/3/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/3/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/2/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/2/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/23/2016'),
new Date('9/5/2016'),
new Date('9/5/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('9/12/2016'),
new Date('9/23/2016'),
new Date('9/12/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/1/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016')
]
},
{
// Should require maintenance
id: 5,
lastTireChange: new Date('9/1/2016'),
manufacturer: 'BazPlane',
landings: [
new Date('9/1/2015'),
new Date('9/5/2015'),
new Date('9/12/2016'),
new Date('9/12/2015'),
new Date('1/1/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016'),
new Date('10/2/2016')
]
},
{
// Should not require maintenance
id: 6,
lastTireChange: new Date('10/29/2016'),
manufacturer: 'BazPlane',
landings: [
new Date('9/1/2015'),
new Date('9/5/2015'),
new Date('9/12/2016'),
new Date('9/12/2015'),
new Date('1/1/2016'),
new Date('10/1/2015'),
new Date('10/23/2015'),
new Date('9/12/2016'),
new Date('10/28/2015'),
new Date('11/15/2015'),
new Date('12/22/2015'),
]
},
]
};
})();
我正试图获得R1和R4之间的所有最短路径。但是，我只获得一条最短路径（R1-R2-R4），而不是（R1-R3-R4）。我需要模拟ECMP（比如OSPF）。我需要的是函数shortestPath返回所有最短路径（即[[R1-R2-R4]，[R1-R3-R4]]）在等价多路径的情况下（如图2上面）和只有最短路径的情况单路径的例如：
graph_2 = {
'R1':{'R2':5,'R3':5},
'R2':{'R1':5,'R4':5},
'R3':{'R1':5,'R4':5},
'R4':{'R2':5,'R3':5},
}
我修改了Dijkstra函数中的代码：
graph_3 = {
'R1':{'R2':5,'R3':5},
'R2':{'R1':5,'R4':5},
'R3':{'R1':5,'R4':10},
'R4':{'R2':5,'R3':5},
}
我收到以下输出和错误：
from priodict import priorityDictionary
graph_2 = {
'R1':{'R2':5,'R3':5},
'R2':{'R1':5,'R4':5},
'R3':{'R1':5,'R4':5},
'R4':{'R2':5,'R3':5},
}
def Dijkstra(G,start,end=None):
D = {} # dictionary of final distances
P = {} # dictionary of predecessors
Q = priorityDictionary() # est.dist. of non-final vert.
Q[start] = 0
for v in Q:
D[v] = Q[v]
if v == end: break
for w in G[v]:
vwLength = D[v] + G[v][w]
if w in D:
if vwLength < D[w]:
raise ValueError, \
elif w not in Q or vwLength < Q[w]:
Q[w] = vwLength
P[w] = [v]
elif w not in Q or vwLength == Q[w]: <---adding this part
Q[w] = vwLength
P[w] += [v]
return (D,P)
def shortestPath(G,start,end):
D,P = Dijkstra(G,start,end)
print D,P
Path = []
while 1:
Path.append(end)
print end
if end == start: break
end = P[end]
Path.reverse()
return Path
print shortestPath(graph_2,'R1','R4')
我想使用graph_2获得的是：
[['R1'，'R2'，'R4']，['R1'，'R3'，'R4']]
并使用graph_3：
[['R1'，'R2'，'R4']]
如果我按原样执行代码，即没有任何代码修改，我得到以下结果，无论我使用graph_2还是graph_3：
[['R1'，'R2'，'R4']]
即使是最短的路径，即使有多条路径。
我知道列表不能成为字典中的关键字，但说实话我坚持这一点，所以任何帮助都非常受欢迎
答案 0 :(得分：0)
<强>分析
感谢您提供可运行的代码。您还没有解释您的设计，但功能问题足够清楚： P 负责返回当前路径上任何给定节点的前任。由于路径是严格线性的，因此只能有一个前驱。 shortestPath 中的 while 循环取决于此。
但是，您返回的 P 列出了当前路径中 R4 的两个前辈，您立即尝试索引 P 同时使用它们。你做不到;你必须单独处理每条路径。
<强>解
简单地修改代码就等于为你做功课;即不酷。既然你已经这么远了，我建议你改变 shortestPath 中的循环来处理多个路径。首先要考虑返回值的每个，然后一次一个：
while True:
for node in end:
# continue with single-path code
编码注释
是的，我将循环条件从 1 更改为 True 。 您使用的食谱似乎是由翻译自 C 或其他早期第3代语言的人编写的，而不会学习当前的编码改进。单字母变量名，大写字母等是当今程序员不合标准的习惯。 （我自己必须重新学习一些。）
要了解您可以采用的方法，请参阅PEP-8。
答案 1 :(得分：0)
最后，我想我得到了我想要的东西:)
这是最终的代码
json以及每个图表的输出：
from priodict import priorityDictionary
from collections import defaultdict
from collections import OrderedDict
import sys
graph_2 = {
'R1':{'R2':5,'R3':5},
'R2':{'R1':5,'R4':5},
'R3':{'R1':5,'R4':5},
'R4':{'R2':5,'R3':5,'R5':5},
'R5':{'R4':5}
}
graph_3 = {
'192.168.255.1':{'192.168.255.2':10,'192.168.255.3':10},
'192.168.255.2':{'192.168.255.1':10,'192.168.255.3':50},
'192.168.255.3':{'192.168.255.1':20,'192.168.255.2':50},
'192.168.255.4':{'192.168.255.3':20},
'192.168.255.3':{'192.168.255.4':20}
}
graph_4 = {
'R1':{'R2':5},
'R2':{'R1':5},
'R2':{'R3':5},
'R3':{'R2':5},
'R3':{'R4':5},
'R4':{'R3':5}
}
graph_5 = {
'A':{'B':5,'C':10,'E':2},
'B':{'A':5,'C':5},
'C':{'B':5,'A':10,'E':8,'D':4},
'D':{'C':4,'E':5},
'E':{'A':2,'D':5,'C':8}
}
def Dijkstra(g,start,end=None):
d = {} # dictionary of final distances
p = {} # dictionary of predecessors
q = priorityDictionary() # est.dist. of non-final vert.
q[start] = 0
for v in q:
d[v] = q[v]
if v == end: break
for w in g[v]:
vwLength = d[v] + g[v][w]
if w in d:
if vwLength < d[w]:
raise ValueError
elif w not in q or vwLength < q[w]:
q[w] = vwLength
p[w] = [v]
elif w not in q or vwLength == q[w]:
q[w] = vwLength
p[w] += [v]
return (d,p)
def shortestPath(g,start,end):
d,p = Dijkstra(g,start,end)
path = [[end]]
while True:
if len(p[end]) > 1:
path.append(p[end])
for node in p[end]:
if node != start:
if ''.join(p[end]) == start: break
end = node
path.append(p[end])
if ''.join(p[end]) == start: break
for node in p[end]:
if node == start: break
end = node
return path[::-1]
print shortestPath(graph_2,'R1','R5')
print shortestPath(graph_3,'192.168.255.1','192.168.255.2')
print shortestPath(graph_4,'R1','R4')
print shortestPath(graph_5,'A','C')