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floyd_warshall.py
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floyd_warshall.py
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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)