Merge pull request #166 from dunderbruno/master

Dijkstra's algorithm

Author: ionicc

Graph_Algorithms/src/Dijkstra/dijkstra.py

@@ -0,0 +1,45 @@
+"""Dijkstra's algorithm."""
+
+import math
+
+
+class Vertex:
+
+    def __init__(self, id):
+        self.id = str(id)
+        self.distance = 0
+        self.neighbors = []
+        self.edges = {}  # {vertex:distance}
+
+    def __lt__(self, other):
+        """Comparison rule to < operator."""
+        return self.distance < other.distance
+
+    def __repr__(self):
+        """Return the vertex id."""
+        return self.id
+
+    def add_neighbor(self, vertex):
+        """Add a pointer to a vertex at neighbor's list."""
+        self.neighbors.append(vertex)
+
+    def add_edge(self, vertex, weight):
+        """Destination vertex and weight."""
+        self.edges[vertex.id] = weight
+
+
+def dijkstra(graph, source, destiny):
+    """Dijkstra's Algorithm."""
+    q = []
+    for v in graph:
+        v.distance = math.inf
+        q.append(v)
+    source.distance = 0
+    while q:
+        v = min(q)
+        q.remove(v)
+        for u in v.neighbors:
+            new = v.distance + v.edges[u.id]
+            if new < u.distance:
+                u.distance = new
+    return destiny.distance