Merge pull request #300 from free-free/master

Update 31_bfs_dfs

Author: wangzheng0822

python/31_bfs_dfs/graph.py

@@ -0,0 +1,75 @@
+# -*- coding:utf-8 -*-
+
+
+class Undigraph(object):
+
+
+    def __init__(self, vertex_num):
+        self.v_num = vertex_num
+        self.adj_tbl = []
+        for i in range(self.v_num + 1):
+            self.adj_tbl.append([])
+
+    def add_edge(self, s, t):
+        if s > self.v_num or t > self.v_num:
+            return False
+        self.adj_tbl[s].append(t)
+        self.adj_tbl[t].append(s)
+        return True
+    
+    def __len__(self):
+        return self.v_num
+
+    def __getitem__(self, ind):
+        if ind > self.v_num:
+            raise IndexError("No Such Vertex!")
+        return self.adj_tbl[ind]
+
+    def __repr__(self):
+        return str(self.adj_tbl)
+
+    def __str__(self):
+        return str(self.adj_tbl)
+
+
+class Digraph(object):
+
+
+    def __init__(self, vertex_num):
+        self.v_num = vertex_num
+        self.adj_tbl = []
+        for i in range(self.v_num + 1):
+            self.adj_tbl.append([])
+    
+    def add_edge(self, frm, to):
+        if frm > self.v_num or to > self.v_num:
+            return False
+        self.adj_tbl[frm].append(to)
+
+    def __len__(self):
+        return self.v_num
+
+    def __getitem__(self, ind):
+        if ind > self.v_num:
+            raise IndexError("No such vertex!")
+        return self.ajd_tbl[ind]
+
+    def __repr__(self):
+        return str(self.adj_tbl)
+
+    def __str__(self):
+        return str(self.adj_tbl)
+
+
+if __name__ == '__main__':
+    ug = Undigraph(10)
+    ug.add_edge(1, 9)
+    ug.add_edge(1, 3)
+    ug.add_edge(3, 2)
+    print(ug.adj_tbl)
+    
+    dg = Digraph(10)
+    dg.add_edge(1, 9)
+    dg.add_edge(1, 3)
+    dg.add_edge(3, 4)
+    print(dg.adj_tbl)

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))