From ac111ee463065e372ad148dbafba630045ecf94c Mon Sep 17 00:00:00 2001
From: Maxim Smolskiy <mithridatus@mail.ru>
Date: Wed, 29 Mar 2023 00:41:54 +0300
Subject: [PATCH] Reduce the complexity of graphs/bi_directional_dijkstra.py
 (#8165)

* Reduce the complexity of graphs/bi_directional_dijkstra.py

* Try to lower the --max-complexity threshold in the file .flake8

* Lower the --max-complexity threshold in the file .flake8

* updating DIRECTORY.md

* updating DIRECTORY.md

* Try to lower max-complexity

* Try to lower max-complexity

* Try to lower max-complexity

---------

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
---
 graphs/bi_directional_dijkstra.py | 93 +++++++++++++++++--------------
 pyproject.toml                    |  2 +-
 2 files changed, 52 insertions(+), 43 deletions(-)

diff --git a/graphs/bi_directional_dijkstra.py b/graphs/bi_directional_dijkstra.py
index fc53e2f0..a4489026 100644
--- a/graphs/bi_directional_dijkstra.py
+++ b/graphs/bi_directional_dijkstra.py
@@ -17,6 +17,32 @@ from typing import Any
 import numpy as np
 
 
+def pass_and_relaxation(
+    graph: dict,
+    v: str,
+    visited_forward: set,
+    visited_backward: set,
+    cst_fwd: dict,
+    cst_bwd: dict,
+    queue: PriorityQueue,
+    parent: dict,
+    shortest_distance: float | int,
+) -> float | int:
+    for nxt, d in graph[v]:
+        if nxt in visited_forward:
+            continue
+        old_cost_f = cst_fwd.get(nxt, np.inf)
+        new_cost_f = cst_fwd[v] + d
+        if new_cost_f < old_cost_f:
+            queue.put((new_cost_f, nxt))
+            cst_fwd[nxt] = new_cost_f
+            parent[nxt] = v
+        if nxt in visited_backward:
+            if cst_fwd[v] + d + cst_bwd[nxt] < shortest_distance:
+                shortest_distance = cst_fwd[v] + d + cst_bwd[nxt]
+    return shortest_distance
+
+
 def bidirectional_dij(
     source: str, destination: str, graph_forward: dict, graph_backward: dict
 ) -> int:
@@ -51,53 +77,36 @@ def bidirectional_dij(
     if source == destination:
         return 0
 
-    while queue_forward and queue_backward:
-        while not queue_forward.empty():
-            _, v_fwd = queue_forward.get()
-
-            if v_fwd not in visited_forward:
-                break
-        else:
-            break
+    while not queue_forward.empty() and not queue_backward.empty():
+        _, v_fwd = queue_forward.get()
         visited_forward.add(v_fwd)
 
-        while not queue_backward.empty():
-            _, v_bwd = queue_backward.get()
-
-            if v_bwd not in visited_backward:
-                break
-        else:
-            break
+        _, v_bwd = queue_backward.get()
         visited_backward.add(v_bwd)
 
-        # forward pass and relaxation
-        for nxt_fwd, d_forward in graph_forward[v_fwd]:
-            if nxt_fwd in visited_forward:
-                continue
-            old_cost_f = cst_fwd.get(nxt_fwd, np.inf)
-            new_cost_f = cst_fwd[v_fwd] + d_forward
-            if new_cost_f < old_cost_f:
-                queue_forward.put((new_cost_f, nxt_fwd))
-                cst_fwd[nxt_fwd] = new_cost_f
-                parent_forward[nxt_fwd] = v_fwd
-            if nxt_fwd in visited_backward:
-                if cst_fwd[v_fwd] + d_forward + cst_bwd[nxt_fwd] < shortest_distance:
-                    shortest_distance = cst_fwd[v_fwd] + d_forward + cst_bwd[nxt_fwd]
+        shortest_distance = pass_and_relaxation(
+            graph_forward,
+            v_fwd,
+            visited_forward,
+            visited_backward,
+            cst_fwd,
+            cst_bwd,
+            queue_forward,
+            parent_forward,
+            shortest_distance,
+        )
 
-        # backward pass and relaxation
-        for nxt_bwd, d_backward in graph_backward[v_bwd]:
-            if nxt_bwd in visited_backward:
-                continue
-            old_cost_b = cst_bwd.get(nxt_bwd, np.inf)
-            new_cost_b = cst_bwd[v_bwd] + d_backward
-            if new_cost_b < old_cost_b:
-                queue_backward.put((new_cost_b, nxt_bwd))
-                cst_bwd[nxt_bwd] = new_cost_b
-                parent_backward[nxt_bwd] = v_bwd
-
-            if nxt_bwd in visited_forward:
-                if cst_bwd[v_bwd] + d_backward + cst_fwd[nxt_bwd] < shortest_distance:
-                    shortest_distance = cst_bwd[v_bwd] + d_backward + cst_fwd[nxt_bwd]
+        shortest_distance = pass_and_relaxation(
+            graph_backward,
+            v_bwd,
+            visited_backward,
+            visited_forward,
+            cst_bwd,
+            cst_fwd,
+            queue_backward,
+            parent_backward,
+            shortest_distance,
+        )
 
         if cst_fwd[v_fwd] + cst_bwd[v_bwd] >= shortest_distance:
             break
diff --git a/pyproject.toml b/pyproject.toml
index 23fe45e9..48c3fbd4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -61,7 +61,7 @@ show-source = true
 target-version = "py311"
 
 [tool.ruff.mccabe]   # DO NOT INCREASE THIS VALUE
-max-complexity = 20  # default: 10
+max-complexity = 17  # default: 10
 
 [tool.ruff.pylint]   # DO NOT INCREASE THESE VALUES
 max-args = 10        # default: 5