[BOJ] 21608 상어 초등학교 (G5)

Author: poodlepoodle

최어진/8주차/260222.py

@@ -0,0 +1,97 @@
+# 백준 21608번: 상어 초등학교 (3회차)
+
+import sys
+
+input = sys.stdin.readline
+
+# N <= 20
+N = int(input())
+maps = [[False for _ in range(N)] for _ in range(N)]
+students = []
+favorites = {}
+for _ in range(N**2):
+    student_num, *student_favorites = map(int, input().rstrip().split())
+    students.append(student_num)
+    favorites[student_num] = student_favorites
+
+# 브루트포싱
+#   1. N**2명의 학생 자리를 정함 -> O(N^2)
+#   2. 각 학생마다 모든 가능한 자리를 검사 -> O(N^2)
+#   결론: O(N^4)
+
+moves = [
+    [0, 1],
+    [0, -1],
+    [1, 0],
+    [-1, 0]
+]
+
+def print_seats():
+    for row in maps:
+        print(row)
+    print()
+
+def is_in_board(r, c):
+    return 0 <= r < N and 0 <= c < N
+
+def get_nearest_favorites(r, c, favorites):
+    cnt = 0
+    for dr, dc in moves:
+        if is_in_board(r + dr, c + dc) and maps[r + dr][c + dc]:
+            if maps[r + dr][c + dc] in favorites: cnt += 1
+    return cnt
+
+def get_nearest_empty_seats(r, c):
+    cnt = 0
+    for dr, dc in moves:
+        if is_in_board(r + dr, c + dc):
+            if not maps[r + dr][c + dc]: cnt += 1
+    return cnt
+
+def check_new_seat(favorites):
+    max_favorites = -1
+    max_emptys = -1
+    seats = [-1, -1]
+
+    for r in range(N):
+        for c in range(N):
+            if maps[r][c]: continue
+            
+            nearest_favorites = get_nearest_favorites(r, c, favorites)
+            nearest_emptys = get_nearest_empty_seats(r, c)
+
+            if nearest_favorites > max_favorites:
+                # print(f'* 친한 친구가 {nearest_favorites}명으로 가장 많은 자리 -> {(r, c)}')
+                max_favorites = nearest_favorites
+                max_emptys = nearest_emptys
+                seats = [r, c]
+            elif nearest_favorites == max_favorites:
+                if nearest_emptys > max_emptys:
+                    # print(f'* 빈 자리가 {nearest_emptys}개로 가장 많은 자리 -> {(r, c)}')
+                    max_emptys = nearest_emptys
+                    seats = [r, c]
+
+    return seats
+
+def get_satisfying():
+    sums = 0
+    for r in range(N):
+        for c in range(N):
+            student_num = maps[r][c]
+            student_favorites = favorites[student_num]
+            score = get_nearest_favorites(r, c, student_favorites)
+
+            if score >= 4: sums += 1000
+            elif score >= 3: sums += 100
+            elif score >= 2: sums += 10
+            elif score: sums += 1
+    return sums
+
+for num in students:
+    student_favorites = favorites[num]
+    # print(f'{num}번 학생: {set(student_favorites)}')
+    r, c = check_new_seat(set(student_favorites))
+    maps[r][c] = num
+    # print_seats()
+
+print(get_satisfying())