codetree.ai 삼성전자 2025 하반기 오후 2번 문제 가로등 설치

문제 링크: https://www.codetree.ai/ko/frequent-problems/all/problems/street-light-installation

Author: skysign

codetree.ai 삼성전자 2025 하반기 오후 2번 문제 가로등 설치/main.py

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+import math
+
+
+def solve():
+    cnt_cmds = int(input().strip())
+    N, M, streetlights = 0, 0, []
+
+    for _ in range(cnt_cmds):
+        tmps = list(map(int, input().strip().split(' ')))
+        cmd = tmps[0]
+
+        if cmd == 100:
+            N, M = tmps[1], tmps[2]
+            mx_M = M
+
+            for idx in range(len(tmps[3:])):
+                streetlights.append([idx + 1, tmps[3:][idx]])
+        elif cmd == 200:
+            M += 1
+            mx_M += 1
+            new_streetlight = [0, 0, M]
+            for idx in range(len(streetlights) - 1):
+                if idx == 0:
+                    left, right = 1, streetlights[idx + 1][1]
+                elif 0 < idx < len(streetlights) - 1:
+                    left, right = streetlights[idx - 1][1], streetlights[idx + 1][1]
+
+                local_delta, local_Ln, local_idx = 0, 0, 0
+
+                if streetlights[idx][1] - left >= right - streetlights[idx][1]:
+                    local_delta = streetlights[idx][1] - left
+                    local_Ln = math.ceil((left + streetlights[idx][1]) / 2)
+                    local_idx = idx
+                else:
+                    local_delta = right - streetlights[idx][1]
+                    local_Ln = math.ceil((streetlights[idx][1] + right) / 2)
+                    local_idx = idx + 1
+
+                if new_streetlight[0] < local_delta:
+                    new_streetlight[0], new_streetlight[1], new_streetlight[2] = local_delta, local_Ln, local_idx
+                elif new_streetlight[0] == local_delta:
+                    if new_streetlight[1] > local_Ln:
+                        new_streetlight[0], new_streetlight[1], new_streetlight[2] = local_delta, local_Ln, local_idx
+
+            if new_streetlight[2] < len(streetlights):
+                streetlights = streetlights[0:new_streetlight[2]] + [[mx_M, new_streetlight[1]]] + streetlights[new_streetlight[2]:]
+            else:
+                streetlights = streetlights + [[M, new_streetlight[1]]]
+
+        elif cmd == 300:
+            D = tmps[1]
+            idx = -1
+            for i in range(len(streetlights)):
+                if streetlights[i][0] == D:
+                    idx = i
+                    break
+
+            streetlights.pop(idx)
+            M -= 1
+
+        elif cmd == 400:
+            mx_r = 0
+            for idx in range(len(streetlights)):
+                if idx == 0:
+                    left, right = 1, streetlights[idx + 1][1]
+                    r = max(streetlights[idx][1] - left, (right - streetlights[idx][1]) / 2)
+                elif 0 < idx < len(streetlights) - 1:
+                    left, right = streetlights[idx - 1][1], streetlights[idx + 1][1]
+                    r = max((streetlights[idx][1] - left) / 2, (right - streetlights[idx][1]) / 2)
+                else:  # if idx == len(streetlights)-1
+                    left, right = streetlights[idx - 1][1], N
+                    r = max((streetlights[idx][1] - left) / 2, right - streetlights[idx][1])
+
+                mx_r = max(mx_r, r)
+
+            print(round(mx_r * 2))
+
+
+if __name__ == '__main__':
+    solve()

codetree.ai 삼성전자 2025 하반기 오후 2번 문제 가로등 설치/test1.txt

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+9
+100 100 3 3 10 90
+400
+200
+200
+400
+300 3
+400
+200
+400

codetree.ai 삼성전자 2025 하반기 오후 2번 문제 가로등 설치/test1_answer.txt

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+80
+40
+100
+100

codetree.ai 삼성전자 2025 하반기 오후 2번 문제 가로등 설치/test2.txt

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+12
+100 10 2 1 10
+400
+200
+400
+200
+400
+200
+400
+300 3
+400
+300 1
+400

codetree.ai 삼성전자 2025 하반기 오후 2번 문제 가로등 설치/test2_answer.txt

@@ -0,0 +1,6 @@
+9
+5
+4
+3
+4
+6

codetree.ai 삼성전자 2025 하반기 오후 2번 문제 가로등 설치/test_main.py

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+import sys
+from pathlib import Path
+from unittest import TestCase
+from main import solve
+
+
+class Test(TestCase):
+    def my_solve(self, testcase_input):
+        sys.stdin = open(testcase_input, 'r')
+        stdout = sys.stdout
+        sys.stdout = open('stdout.txt', 'w')
+        solve()
+        sys.stdout.close()
+        sys.stdout = stdout
+
+    def test_solve(self, testcase_number: str):
+        self.my_solve('test' + testcase_number + '.txt')
+        self.assertEqual(
+            Path('test' + testcase_number + '_answer.txt').read_text().strip(),
+            Path('stdout.txt').read_text().strip())
+
+    def test1_solve(self):
+        self.test_solve('1')
+
+    def test2_solve(self):
+        self.test_solve('2')