Showing posts with label graph. Show all posts
Showing posts with label graph. Show all posts

Dijkstra’s shortest path algorithm

import sys

class Graph():

def __init__(self, vertices):

self.V = vertices

self.graph = [[0 for column in range(vertices)]

for row in range(vertices)]

def printSolution(self, dist):

print("Vertex \tDistance from Source")

for node in range(self.V):

print(node, "\t", dist[node])

def minDistance(self, dist, sptSet):

min = sys.maxsize

for u in range(self.V):

if dist[u] < min and sptSet[u] == False:

min = dist[u]

min_index = u

return min_index

def dijkstra(self, src):

dist = [sys.maxsize] * self.V

dist[src] = 0

sptSet = [False] * self.V

for cout in range(self.V):

x = self.minDistance(dist, sptSet)

sptSet[x] = True

for y in range(self.V):

if self.graph[x][y] > 0 and sptSet[y] == False and \

dist[y] > dist[x] + self.graph[x][y]:

dist[y] = dist[x] + self.graph[x][y]

self.printSolution(dist)

g = Graph(9)

g.graph = [[0, 4, 0, 0, 0, 0, 0, 8, 0],

[4, 0, 8, 0, 0, 0, 0, 11, 0],

[0, 8, 0, 7, 0, 4, 0, 0, 2],

[0, 0, 7, 0, 9, 14, 0, 0, 0],

[0, 0, 0, 9, 0, 10, 0, 0, 0],

[0, 0, 4, 14, 10, 0, 2, 0, 0],

[0, 0, 0, 0, 0, 2, 0, 1, 6],

[8, 11, 0, 0, 0, 0, 1, 0, 7],

[0, 0, 2, 0, 0, 0, 6, 7, 0]

];


g.dijkstra(0);