programmers.co.kr 코딩테스트 연습_동적계획법(Dynamic Programming)_N으로 표현

문제 링크: https://school.programmers.co.kr/learn/courses/30/lessons/42895

Author: skysign

programmers.co.kr 코딩테스트 연습_동적계획법(Dynamic Programming)_N으로 표현/main.py

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+import copy
+from collections import defaultdict
+from typing import List, Dict
+
+
+def solution(N: int, number: int):
+    # X / N 의 값이 number의 최소값이 될 수 있음
+    # 따라서, number * N + 1 이 dp의 최소 길이
+    l = number * N + 1
+    dp: List[int] = [9] * l
+
+    dp[N] = 1
+    dp[1] = min(dp[1], 2)  # N/N, N이 1인 경우도 고려해서, min()이 필요함
+
+    # NN, NNN등의 숫자 처리필요함
+    str = '{:d}'.format(N)
+    cntN = 1
+
+    while int(str) <= l:
+        dp[int(str)] = min(dp[int(str)], cntN)
+        str += '{:d}'.format(N)
+        cntN += 1
+
+    def do_plus():
+        for i in range(l - 1, 0, -1):
+            if dp[i] <= 8 and 1 <= i + N < l:
+                dp[i + N] = min(dp[i + N], dp[i] + 1)
+
+    def do_multiply():
+        for i in range(l - 1, 0, -1):
+            if dp[i] <= 8 and 1 <= i * N < l:
+                dp[i * N] = min(dp[i * N], dp[i] + 1)
+
+    def do_minus():
+        for i in range(1, l):
+            if dp[i] <= 8 and 1 <= i - N < l:
+                dp[i - N] = min(dp[i - N], dp[i] + 1)
+
+    def do_divide():
+        for i in range(1, l):
+            if dp[i] <= 8 and 1 <= i // N < l:
+                dp[i // N] = min(dp[i // N], dp[i] + 1)
+
+    for _ in range(8):
+        do_plus()
+        do_multiply()
+        do_minus()
+        do_divide()
+
+    dict: Dict = defaultdict(lambda: 9)
+
+    for i in range(1, l):
+        if dp[i] > 8:
+            continue
+        else:
+            dict[i] = dp[i]
+
+    dict_local: Dict = copy.deepcopy(dict)
+    li = list(dict.keys())
+    lj = list(dict.keys())
+    li.sort()
+    lj.sort()
+
+    for i in li:
+        for j in lj:
+            if i == j:
+                continue
+
+            vs = [i + j, i * j, i // j, i - j,
+                  j + i, j * i, j // i, j - i]
+            for v in vs:
+                if 1 <= v < l:
+                    dict_local[v] = min(dict_local[v], dict[i] + dict[j])
+                    if dict_local[v] > 8:
+                        del dict_local[v]
+
+    dict = dict_local
+
+    if dict[number] > 8:
+        return -1
+
+    return dict[number]

programmers.co.kr 코딩테스트 연습_동적계획법(Dynamic Programming)_N으로 표현/test_main.py

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+from unittest import TestCase
+from main import solution
+
+
+class Test(TestCase):
+    def test1_solution(self):
+        self.assertEqual(4, solution(5, 12))
+
+    def test2_solution(self):
+        self.assertEqual(3, solution(2, 11))
+
+    def testa_solution(self):
+        self.assertEqual(-1, solution(5, 31168))
+
+    # https://school.programmers.co.kr/questions/30926
+    # 4, 31
+    # (4 + 4) * 4 - (4 / 4)
+    def test_a1_solution(self):
+        self.assertEqual(5, solution(4, 31))
+
+    # https://school.programmers.co.kr/questions/56476
+    def test_b1_solution(self):
+        self.assertEqual(4, solution(1, 121))
+
+    def test_b2_solution(self):
+        self.assertEqual(4, solution(5, 3025))
+
+    def test_b3_solution(self):
+        self.assertEqual(5, solution(5, 3125))
+
+    # def test_b4_solution(self):
+    #     self.assertEqual(2, solution(9, 0))
+
+    # https://school.programmers.co.kr/questions/43922
+    def test_c1_solution(self):
+        self.assertEqual(3, solution(6, 5))