Update m_coloring_problem.py

Author: sgindeed

backtracking/m_coloring_problem.py

@@ -1,6 +1,5 @@
-def is_safe(
-    node: int, color: int, graph: list[list[int]], num_vertices: int, col: list[int]
-) -> bool:
+def is_safe(node: int, color: int, graph: list[list[int]], num_vertices: int,
+            col: list[int]) -> bool:
     """
     Check if it is safe to assign a color to a node.
 
@@ -9,18 +8,12 @@ def is_safe(
     >>> is_safe(0, 2, [[0,1],[1,0]], 2, [0,1])
     True
     """
-    return all(
-        not (graph[node][k] == 1 and col[k] == color) for k in range(num_vertices)
-    )
-
-
-def solve(
-    node: int,
-    col: list[int],
-    max_colors: int,
-    num_vertices: int,
-    graph: list[list[int]],
-) -> bool:
+    return all(not (graph[node][k] == 1 and col[k] == color)
+               for k in range(num_vertices))
+
+
+def solve(node: int, col: list[int], max_colors: int, num_vertices: int,
+          graph: list[list[int]]) -> bool:
     """
     Recursively try to color the graph using at most max_colors.
 
@@ -40,7 +33,8 @@ def solve(
     return False
 
 
-def graph_coloring(graph: list[list[int]], max_colors: int, num_vertices: int) -> bool:
+def graph_coloring(graph: list[list[int]], max_colors: int,
+                   num_vertices: int) -> bool:
     """
     Determine if the graph can be colored with at most max_colors.
 
@@ -51,3 +45,20 @@ def graph_coloring(graph: list[list[int]], max_colors: int, num_vertices: int) -
     """
     col = [0] * num_vertices
     return solve(0, col, max_colors, num_vertices, graph)
+
+
+if __name__ == "__main__":
+    print("Graph Coloring Problem")
+    num_vertices = int(input("Enter number of vertices: "))
+    num_edges = int(input("Enter number of edges: "))
+    print("Enter each edge as 'u v' (0-based indexing):")
+    graph = [[0]*num_vertices for _ in range(num_vertices)]
+    for _ in range(num_edges):
+        u, v = map(int, input().split())
+        graph[u][v] = 1
+        graph[v][u] = 1
+    max_colors = int(input("Enter maximum number of colors: "))
+    if graph_coloring(graph, max_colors, num_vertices):
+        print(f"The graph can be colored with {max_colors} colors.")
+    else:
+        print(f"The graph cannot be colored with {max_colors} colors.")