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105 lines
2.6 KiB
Python
105 lines
2.6 KiB
Python
def print_dist(dist, v):
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"""
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Print vertex distances.
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Parameters:
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dist (list): A list of distances.
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v (int): The number of vertices.
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Example:
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>>> print_dist([0.0, 2.0, 3.0, float('inf')], 4)
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Vertex Distance
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0 0
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1 2
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2 3
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3 INF
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"""
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print("\nVertex Distance")
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for i in range(v):
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if dist[i] != float("inf"):
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print(i, "\t", int(dist[i]), end="\t")
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else:
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print(i, "\t", "INF", end="\t")
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print()
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def min_dist(mdist, vset, v):
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"""
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Find the vertex with the minimum distance.
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Parameters:
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mdist (list): A list of distances.
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vset (list): A list of boolean values indicating visited vertices.
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v (int): The number of vertices.
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Example:
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>>> min_dist([0.0, 2.0, 3.0, float('inf')], [False, True, False, False], 4)
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0
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"""
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min_val = float("inf")
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min_ind = -1
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for i in range(v):
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if (not vset[i]) and mdist[i] < min_val:
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min_ind = i
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min_val = mdist[i]
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return min_ind
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def dijkstra(graph, v, src):
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"""
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Implement Dijkstra's algorithm to find the shortest path.
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Parameters:
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graph (list): The graph represented as an adjacency matrix.
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v (int): The number of vertices.
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src (int): The source vertex.
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Example:
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>>> graph = [[0.0, 2.0, float('inf'), 1.0], [2.0, 0.0, 4.0, float('inf')], [float('inf'), 4.0, 0.0, 3.0], [1.0, float('inf'), 3.0, 0.0]]
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>>> dijkstra(graph, 4, 0)
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Vertex Distance
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0 0
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1 2
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2 3
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3 1
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"""
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mdist = [float("inf") for _ in range(v)]
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vset = [False for _ in range(v)]
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mdist[src] = 0.0
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for _ in range(v - 1):
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u = min_dist(mdist, vset, v)
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vset[u] = True
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for i in range(v):
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if (
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(not vset[i])
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and graph[u][i] != float("inf")
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and mdist[u] + graph[u][i] < mdist[i]
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):
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mdist[i] = mdist[u] + graph[u][i]
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print_dist(mdist, i)
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if __name__ == "__main__":
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V = int(input("Enter number of vertices: ").strip())
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E = int(input("Enter number of edges: ").strip())
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graph = [[float("inf") for i in range(V)] for j in range(V)]
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for i in range(V):
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graph[i][i] = 0.0
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for i in range(E):
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print("\nEdge ", i + 1)
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src = int(input("Enter source:").strip())
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dst = int(input("Enter destination:").strip())
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weight = float(input("Enter weight:").strip())
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graph[src][dst] = weight
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gsrc = int(input("\nEnter shortest path source:").strip())
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dijkstra(graph, V, gsrc)
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