Python Dijkstra算法

( VISIT_WHITE, VISIT_GRAY, VISIT_BLACK ) = ( 0, 1, 2 )
NO_ROAD = 1 << 31

class CityNode:

def __init__( self ):

self.m_iDist = 1 << 31
self.m_iParent = 0
self.m_visit = VISIT_WHITE

def init( graph ):

graph[0][1] = 15; graph[0][3] = 2; graph[0][4] = 12
graph[1][2] = 6; graph[2][6] = 9; graph[3][2] = 8;
graph[3][5] = 4; graph[4][6] = 3; graph[5][6] = 10
graph[5][4] = 5; graph[6][1] = 4

def dijkstra( graph, start_pos ):

city_num = len( graph )
INF = 1 << 31
city_arr = [ CityNode() for index in range( city_num ) ]
count = 0
city_arr[start_pos].m_iDist = 0

while count < city_num:

temp_min = INF
next_pos = -1

for index in range( city_num ):
if temp_min > city_arr[index].m_iDist \
and city_arr[index].m_visit != VISIT_BLACK:

temp_min = city_arr[index].m_iDist
next_pos = index

city_arr[next_pos].m_visit = VISIT_BLACK

for index in range( city_num ):
if graph[next_pos][index] != NO_ROAD \
and city_arr[index].m_visit != VISIT_BLACK \
and city_arr[index].m_iDist > city_arr[next_pos].m_iDist + graph[next_pos][index]:

city_arr[index].m_iDist = city_arr[next_pos].m_iDist + graph[next_pos][index]
city_arr[index].m_visit = VISIT_GRAY

count += 1

for index in range( city_num ):
print index, city_arr[index].m_iDist

if __name__ == '__main__':
num = 7
graph = [ [ NO_ROAD for col_index in range( num ) ]for raw_index in range( num ) ]

init( graph )

dijkstra( graph, 0 )