Implement check_bipartite_graph using DFS. (#808)

graphs/check_bipartite_graph_dfs.py

@@ -0,0 +1,33 @@
+# Check whether Graph is Bipartite or Not using DFS
+
+# A Bipartite Graph is a graph whose vertices can be divided into two independent sets,
+# U and V such that every edge (u, v) either connects a vertex from U to V or a vertex
+# from V to U. In other words, for every edge (u, v), either u belongs to U and v to V,
+# or u belongs to V and v to U. We can also say that there is no edge that connects
+# vertices of same set.
+def check_bipartite_dfs(l):
+    visited = [False] * len(l)
+    color = [-1] * len(l)
+
+    def dfs(v, c):
+        visited[v] = True
+        color[v] = c
+        for u in l[v]:
+            if not visited[u]:
+                dfs(u, 1 - c)
+
+    for i in range(len(l)):
+        if not visited[i]:
+            dfs(i, 0)
+
+    for i in range(len(l)):
+        for j in l[i]:
+            if color[i] == color[j]:
+                return False
+
+    return True
+        
+
+# Adjacency list of graph
+l = {0:[1,3], 1:[0,2], 2:[1,3], 3:[0,2], 4: []}
+print(check_bipartite_dfs(l))