Fixes: TheAlgorithms#8098

graphs/check_bipartite_graph_all.py

@@ -0,0 +1,110 @@
+
+''' Check whether Graph is Bipartite or Not using BFS
+ https://www.geeksforgeeks.org/bipartite-graph/
+  Args:
+        graph: An adjacency list representing the graph.
+
+    Returns:
+        True if there's no edge that connects vertices of the same set, False otherwise.
+
+    Examples:
+        >>> is_bipartite(
+        ...     defaultdict(list, {0: [1, 2], 1: [0, 3], 2: [0, 4], 3: [1], 4: [2]})
+        ... )
+        False
+        >>> is_bipartite(defaultdict(list, {0: [1, 2], 1: [0, 2], 2: [0, 1]}))
+        True'''
+from queue import Queue
+
+
+def check_bipartite(graph):
+    queue = Queue()
+    visited = [False] * len(graph)
+    color = [-1] * len(graph)
+
+    def bfs():
+        while not queue.empty():
+            u = queue.get()
+            visited[u] = True
+
+            for neighbour in graph[u]:
+                if neighbour == u:
+                    return False
+
+                if color[neighbour] == -1:
+                    color[neighbour] = 1 - color[u]
+                    queue.put(neighbour)
+
+                elif color[neighbour] == color[u]:
+                    return False
+
+        return True
+
+    for i in range(len(graph)):
+        if not visited[i]:
+            queue.put(i)
+            color[i] = 0
+            if bfs() is False:
+                return False
+
+    return True
+
+
+if __name__ == "__main__":
+    # Adjacency List of graph
+    print(check_bipartite({0: [1, 3], 1: [0, 2], 2: [1, 3], 3: [0, 2]}))
+
+
+from collections import defaultdict
+
+
+def is_bipartite(graph: defaultdict[int, list[int]]) -> bool:
+    """
+    Check whether a graph is Bipartite or not using Depth-First Search (DFS).
+
+    https://www.geeksforgeeks.org/check-if-a-given-graph-is-bipartite-using-dfs/
+
+
+    Args:
+        graph: An adjacency list representing the graph.
+
+    Returns:
+        True if there's no edge that connects vertices of the same set, False otherwise.
+
+    Examples:
+        >>> is_bipartite(
+        ...     defaultdict(list, {0: [1, 2], 1: [0, 3], 2: [0, 4], 3: [1], 4: [2]})
+        ... )
+        False
+        >>> is_bipartite(defaultdict(list, {0: [1, 2], 1: [0, 2], 2: [0, 1]}))
+        True
+    """
+
+    def depth_first_search(node: int, color: int) -> bool:
+        visited[node] = color
+        return any(
+            visited[neighbour] == color
+            or (
+                visited[neighbour] == -1
+                and not depth_first_search(neighbour, 1 - color)
+            )
+            for neighbour in graph[node]
+        )
+
+    visited: defaultdict[int, int] = defaultdict(lambda: -1)
+
+    return all(
+        not (visited[node] == -1 and not depth_first_search(node, 0)) for node in graph
+    )
+
+
+if __name__ == "__main__":
+    import doctest
+
+    result = doctest.testmod()
+
+    if result.failed:
+        print(f"{result.failed} test(s) failed.")
+    else:
+        print("All tests passed!")
+