solved(python): baekjoon 11281

Author: himitery

baekjoon/python/11281/__init__.py

@@ -0,0 +1,102 @@
+import sys
+from collections import defaultdict, deque
+
+read = lambda: sys.stdin.readline().rstrip()
+
+
+class Problem:
+    def __init__(self) -> None:
+        self.n, self.m = map(int, read().split())
+
+        self.graph = defaultdict(list)
+        for x, y in [map(int, read().split()) for _ in range(self.m)]:
+            self.graph[self.literal_to_node(-x)].append(self.literal_to_node(y))
+            self.graph[self.literal_to_node(-y)].append(self.literal_to_node(x))
+
+    def literal_to_node(self, literal: int) -> int:
+        if literal > 0:
+            return literal
+
+        return -literal + self.n
+
+    def solve(self) -> None:
+        discovered, low, scc_id, on_stack, scc_stack, order, scc_counter = (
+            [-1] * (2 * self.n + 1),
+            [-1] * (2 * self.n + 1),
+            [-1] * (2 * self.n + 1),
+            [False] * (2 * self.n + 1),
+            deque(),
+            0,
+            0,
+        )
+
+        for node in range(1, 2 * self.n + 1):
+            if discovered[node] == -1:
+                order, scc_counter = self.tarjan_scc(
+                    node,
+                    discovered,
+                    low,
+                    scc_id,
+                    on_stack,
+                    scc_stack,
+                    order,
+                    scc_counter,
+                )
+
+        for idx in range(1, self.n + 1):
+            if scc_id[idx] == scc_id[idx + self.n]:
+                print(0)
+                return
+
+        print(1)
+        print(*[0 if scc_id[idx] > scc_id[idx + self.n] else 1 for idx in range(1, self.n + 1)])
+
+    def tarjan_scc(
+        self,
+        start_node: int,
+        discovered: list[int],
+        low: list[int],
+        scc_id: list[int],
+        on_stack: list[bool],
+        scc_stack: deque,
+        order: int,
+        scc_counter: int,
+    ) -> tuple[int, int]:
+        stack = deque([(start_node, iter(self.graph[start_node]))])
+
+        while stack:
+            current_node, neighbors = stack[-1]
+
+            if discovered[current_node] == -1:
+                order += 1
+                discovered[current_node] = low[current_node] = order
+                scc_stack.append(current_node)
+                on_stack[current_node] = True
+
+            for neighbor in neighbors:
+                if discovered[neighbor] == -1:
+                    stack.append((neighbor, iter(self.graph[neighbor])))
+                    break
+                elif on_stack[neighbor]:
+                    low[current_node] = min(low[current_node], discovered[neighbor])
+            else:
+                popped_node, _ = stack.pop()
+
+                if low[popped_node] == discovered[popped_node]:
+                    scc_counter += 1
+                    while True:
+                        node_in_scc = scc_stack.pop()
+                        on_stack[node_in_scc] = False
+                        scc_id[node_in_scc] = scc_counter
+                        if node_in_scc == popped_node:
+                            break
+
+                if stack:
+                    parent_node, _ = stack[-1]
+                    low[parent_node] = min(low[parent_node], low[popped_node])
+
+        return order, scc_counter
+
+
+if __name__ == "__main__":
+    Problem().solve()

baekjoon/python/11281/main.py

@@ -0,0 +1,25 @@
+[
+  {
+    "input": [
+      "3 4",
+      "-1 2",
+      "-2 3",
+      "1 3",
+      "3 2"
+    ],
+    "expected": [
+      "1",
+      "1 1 1"
+    ]
+  },
+  {
+    "input": [
+      "1 2",
+      "1 1",
+      "-1 -1"
+    ],
+    "expected": [
+      "0"
+    ]
+  }
+]

baekjoon/python/11281/sample.json

@@ -0,0 +1,36 @@
+import json
+import os.path
+import unittest
+from io import StringIO
+from unittest.mock import patch
+
+from parameterized import parameterized
+
+from main import Problem
+
+
+def load_sample(filename: str):
+    path = os.path.join(os.path.dirname(os.path.abspath(__file__)), filename)
+
+    with open(path, "r") as file:
+        return [(case["input"], case["expected"]) for case in json.load(file)]
+
+
+class TestCase(unittest.TestCase):
+    @parameterized.expand(load_sample("sample.json"))
+    def test_case(self, case: str, expected: list[str]):
+        # When
+        with (
+            patch("sys.stdin.readline", side_effect=case),
+            patch("sys.stdout", new_callable=StringIO) as output,
+        ):
+            Problem().solve()
+
+            result = output.getvalue().rstrip()
+
+        # Then
+        self.assertEqual("\n".join(expected), result)
+
+
+if __name__ == "__main__":
+    unittest.main()