Add function , which is to find all the vertices of one vertex given the specific degree by using broad first search policy

python/31_bfs_dfs/graph_application.py

@@ -0,0 +1,45 @@
+# -*- coding:utf-8 -*-
+
+
+
+from collections import deque
+from graph import Undigraph
+
+def find_vertex_by_degree(graph, s, degree):
+    if len(graph) <= 1:
+        return []
+    if degree == 0:
+        return [s]
+    d_vertices = []
+    queue = deque()
+    prev = [-1] * len(graph)
+    visited = [False] * len(graph)
+    visited[s] = True
+    queue.append(s)
+    while len(queue) > 0:
+        sz = len(queue)
+        for i in range(sz):
+            v = queue.popleft()
+            for adj_v in graph[v]:
+                if not visited[adj_v]:
+                    prev[adj_v] = v
+                    visited[adj_v] = True
+                    queue.append(adj_v)
+        degree -= 1
+        if degree == 0 and len(queue) != 0:
+            return queue 
+
+   
+if __name__ == '__main__':
+    g = Undigraph(8)
+    g.add_edge(0, 1)
+    g.add_edge(0, 3)
+    g.add_edge(1, 2)
+    g.add_edge(1, 4)
+    g.add_edge(2, 5)
+    g.add_edge(3, 4)
+    g.add_edge(4, 5)
+    g.add_edge(4, 6)
+    g.add_edge(5, 7)
+    g.add_edge(6, 7)
+    print(find_vertex_by_degree(g, 0, 4))