correct DFS, proposal type annotations

Makefile

@@ -1,19 +1,19 @@
-help:
+help::
 	@echo "make pycodestyle  run pycodestyle on Python source"
 	@echo "make pylint       run pylint on Python source"
 
-tests:
+tests::
 	python -m unittest 
 
-pycodestyle:
+pycodestyle::
 	-@find setup.py tryalgo -type f -name '*.py' | xargs pycodestyle
 
-pylint:
+pylint::
 	-@find setup.py tryalgo -type f -name '*.py' | xargs pylint --disable=C0103 -j 4
 
 .PHONY: help pycodestyle pylint bin docs
 
-docs:
+docs::
 	cd docs/_static && convert logo_W.png logo_B.png +append logo_white.png
 	sphinx-apidoc -f -o docs/tryalgo tryalgo
 	sphinx-build docs docs/_build

tests/test_tryalgo.py

@@ -48,7 +48,7 @@ def isclose(a, b, rel_tol, abs_tol):
 from tryalgo.ford_fulkerson import ford_fulkerson
 from tryalgo.gale_shapley import gale_shapley
 from tryalgo.gauss_jordan import gauss_jordan, GJ_ZERO_SOLUTIONS, GJ_SINGLE_SOLUTION, GJ_SEVERAL_SOLUTIONS
-from tryalgo.graph import Graph
+from tryalgo.graph import Graph_named_vertices
 from tryalgo.graph01 import dist01
 from tryalgo.horn_sat import horn_sat
 from tryalgo.huffman import huffman
@@ -774,7 +774,7 @@ def test_gauss_jordan(self):
                                       x, [1, 1, 3]), GJ_ZERO_SOLUTIONS)
 
     def test_graph(self):
-        G = Graph()
+        G = Graph_named_vertices()
         G.add_node("A")
         G.add_node("B")
         G.add_node("C")

tryalgo/dfs.py

@@ -6,9 +6,11 @@
 jill-jênn vie et christoph durr - 2015-2019
 """
 
+from typing import List, Optional
+from . graph import Graph
 
 # snip{ dfs-recursive
-def dfs_recursive(graph, node, seen):
+def dfs_recursive(graph: Graph, node: int, seen: List[bool]) -> None:
     """DFS, detect connected component, recursive implementation
 
     :param graph: directed graph in listlist or listdict format
@@ -25,7 +27,7 @@ def dfs_recursive(graph, node, seen):
 
 
 # snip{ dfs-iterative
-def dfs_iterative(graph, start, seen):
+def dfs_iterative_old(graph, start, seen):
     """DFS, detect connected component, iterative implementation
 
     :param graph: directed graph in listlist or listdict format
@@ -44,9 +46,29 @@ def dfs_iterative(graph, start, seen):
                 to_visit.append(neighbor)
 # snip}
 
+# snip{ dfs-iterative
+def dfs_iterative(graph: Graph, start: int, seen: List[int]) -> None:
+    """DFS, detect connected component, iterative implementation
+
+    :param graph: directed graph in listlist or listdict format
+    :param int node: to start graph exploration
+    :param boolean-table seen: will be set true for the connected component
+          containing node.
+    :complexity: `O(|V|+|E|)`
+    """
+    to_visit = [start]
+    while to_visit:
+        node = to_visit.pop()
+        if not seen[node]:
+            for neighbor in reversed(graph[node]):
+                if not seen[neighbor]:
+                    to_visit.append(neighbor)
+            seen[node] = True
+# snip}
+
 
 # snip{ dfs-tree
-def dfs_tree(graph, start=0):
+def dfs_tree(graph: Graph, start: int=0) -> List[int]:
     """DFS, build DFS tree in unweighted graph
 
        :param graph: directed graph in listlist or listdict format
@@ -66,7 +88,7 @@ def dfs_tree(graph, start=0):
 # snip}
 
 
-def dfs_grid_recursive(grid, i, j, mark='X', free='.'):
+def dfs_grid_recursive(grid: List[List[str]], i: int, j: int, mark: str='X', free: str='.') -> None:
     """DFS on a grid, mark connected component, recursive version
 
     :param grid: matrix, 4-neighborhood
@@ -86,7 +108,7 @@ def dfs_grid_recursive(grid, i, j, mark='X', free='.'):
 
 
 # snip{ dfs-grid
-def dfs_grid(grid, i, j, mark='X', free='.'):
+def dfs_grid(grid, i, j, mark='X', free: str='.') -> None:
     """DFS on a grid, mark connected component, iterative version
 
     :param grid: matrix, 4-neighborhood
@@ -111,7 +133,7 @@ def dfs_grid(grid, i, j, mark='X', free='.'):
 
 
 # pylint: disable=too-many-nested-blocks, no-else-return
-def find_cycle(graph):
+def find_cycle(graph: Graph) -> Optional[List[int]]:
     """find a cycle in an undirected graph
 
     :param graph: undirected graph in listlist or listdict format

tryalgo/graph.py

@@ -8,6 +8,8 @@
 # pylint: disable=bad-whitespace, line-too-long, missing-docstring
 # pylint: disable=dangerous-default-value, too-many-locals, too-many-branches
 
+# from __future__ import annotations
+from typing import List, Dict, Type, Union
 
 def readval(file, ty):
     """Reads a line from file with an item of type ty
@@ -353,7 +355,7 @@ def make_flow_labels(graph, flow, capac):
 
 # pylint: disable=arguments-out-of-order
 # snip{ class_graph
-class Graph:
+class Graph_named_vertices:
     def __init__(self):
         self.neighbors = []
         self.name2node = {}
@@ -384,3 +386,5 @@ def add_arc(self, name_u, name_v, weight_uv=None):
         self.neighbors[u].append(v)
         self.weight[u][v] = weight_uv
 # snip}
+
+Graph = Union[List[List[int]], List[Dict[int, int]], Graph_named_vertices]