Python/dynamic_programming/floyd_warshall.py

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Python
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2018-10-19 12:48:28 +00:00
import math
class Graph:
def __init__(self, N = 0): # a graph with Node 0,1,...,N-1
self.N = N
self.W = [[math.inf for j in range(0,N)] for i in range(0,N)] # adjacency matrix for weight
self.dp = [[math.inf for j in range(0,N)] for i in range(0,N)] # dp[i][j] stores minimum distance from i to j
def addEdge(self, u, v, w):
self.dp[u][v] = w
def floyd_warshall(self):
for k in range(0,self.N):
for i in range(0,self.N):
for j in range(0,self.N):
self.dp[i][j] = min(self.dp[i][j], self.dp[i][k] + self.dp[k][j])
def showMin(self, u, v):
return self.dp[u][v]
if __name__ == '__main__':
graph = Graph(5)
graph.addEdge(0,2,9)
graph.addEdge(0,4,10)
graph.addEdge(1,3,5)
graph.addEdge(2,3,7)
graph.addEdge(3,0,10)
graph.addEdge(3,1,2)
graph.addEdge(3,2,1)
graph.addEdge(3,4,6)
graph.addEdge(4,1,3)
graph.addEdge(4,2,4)
graph.addEdge(4,3,9)
graph.floyd_warshall()
graph.showMin(1,4)
graph.showMin(0,3)