solved(python): baekjoon 11438

Author: himitery

baekjoon/python/11438/__init__.py

@@ -0,0 +1,62 @@
+import itertools
+import sys
+from collections import defaultdict, deque
+
+read = lambda: sys.stdin.readline().rstrip()
+
+
+class Problem:
+    def __init__(self):
+        self.n = int(read())
+
+        self.nodes = defaultdict(list[int])
+        for src, dest in [map(lambda x: int(x) - 1, read().split()) for _ in range(self.n - 1)]:
+            self.nodes[src].append(dest)
+            self.nodes[dest].append(src)
+
+        self.queries = [map(lambda x: int(x) - 1, read().split()) for _ in range(int(read()))]
+        self.depth, self.parent = self.make_tree()
+
+    def solve(self) -> None:
+        for x, y in self.queries:
+            print(self.lca(x, y) + 1)
+
+    def make_tree(self):
+        stack, visited = deque([(0, 0)]), {0}
+        depth, parent = [0 for _ in range(self.n)], [[0 for _ in range(17)] for _ in range(self.n)]
+
+        while stack:
+            idx, node = stack.pop()
+            depth[node] = idx
+
+            for next_node in self.nodes[node]:
+                if next_node not in visited:
+                    stack.append((idx + 1, next_node))
+                    visited.add(next_node)
+                    parent[next_node][0] = node
+
+        for k, node in itertools.product(range(1, 17), range(self.n)):
+            parent[node][k] = parent[parent[node][k - 1]][k - 1]
+
+        return depth, parent
+
+    def lca(self, x: int, y: int) -> int:
+        if self.depth[x] < self.depth[y]:
+            x, y = y, x
+
+        for k in range(16, -1, -1):
+            if self.depth[x] - (1 << k) >= self.depth[y]:
+                x = self.parent[x][k]
+
+        if x == y:
+            return x
+
+        for k in range(16, -1, -1):
+            if self.parent[x][k] != self.parent[y][k]:
+                x, y = self.parent[x][k], self.parent[y][k]
+
+        return self.parent[x][0]
+
+
+if __name__ == "__main__":
+    Problem().solve()

baekjoon/python/11438/main.py

@@ -0,0 +1,36 @@
+[
+  {
+    "input": [
+      "15",
+      "1 2",
+      "1 3",
+      "2 4",
+      "3 7",
+      "6 2",
+      "3 8",
+      "4 9",
+      "2 5",
+      "5 11",
+      "7 13",
+      "10 4",
+      "11 15",
+      "12 5",
+      "14 7",
+      "6",
+      "6 11",
+      "10 9",
+      "2 6",
+      "7 6",
+      "8 13",
+      "8 15"
+    ],
+    "expected": [
+      "2",
+      "4",
+      "2",
+      "1",
+      "3",
+      "1"
+    ]
+  }
+]

baekjoon/python/11438/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()