Monikulmio

from collections import deque

def sign(a: int) -> int:
    """Palauttaa luvun etumerkin (-1, 0, 1)."""
    return (a > 0) - (a < 0)

# --- Syöte ---
n, m, k = map(int, input().split())
points = [tuple(map(lambda v: int(v) - 1, input().split())) for _ in range(k)]

# --- Alustetaan ruudukko ---
grid = [['.' for _ in range(m)] for _ in range(n)]

# --- Piirretään janat ja kärkipisteet ---
for i in range(k):
    y1, x1 = points[i]
    y2, x2 = points[(i + 1) % k]
    dy, dx = sign(y2 - y1), sign(x2 - x1)
    y, x = y1, x1

    while True:
        # Kärkipiste
        if (y, x) in points:
            grid[y][x] = '*'
        else:
            # Valitaan merkki suunnan perusteella
            if dy == 0:
                ch = '='
            elif dx == 0:
                ch = '|'
            elif dy == dx:
                ch = '\\'
            else:
                ch = '/'
            grid[y][x] = ch

        if (y, x) == (y2, x2):
            break
        y += dy
        x += dx

# --- Täytetään sisäpuoli BFS:llä ---
visited = [[False]*m for _ in range(n)]
queue = deque()

# Lisätään reunat BFS:n aloituspisteiksi
for y in [0, n-1]:
    for x in range(m):
        if not visited[y][x]:
            visited[y][x] = True
            if grid[y][x] == '.':
                queue.append((y, x))

for x in [0, m-1]:
    for y in range(n):
        if not visited[y][x]:
            visited[y][x] = True
            if grid[y][x] == '.':
                queue.append((y, x))

# BFS: merkitään kaikki ulkopuolella olevat pisteet
while queue:
    y, x = queue.popleft()
    for dy, dx in [(-1,0),(1,0),(0,-1),(0,1)]:
        ny, nx = y+dy, x+dx
        if 0<=ny<n and 0<=nx<m and not visited[ny][nx] and grid[ny][nx]=='.':
            visited[ny][nx] = True
            queue.append((ny, nx))

# Kaikki pisteet, joita ei saavutettu BFS:llä, ovat sisällä
for y in range(n):
    for x in range(m):
        if grid[y][x] == '.' and not visited[y][x]:
            grid[y][x] = '#'

# --- Tulostus ---
for row in grid:
    print(''.join(row))

Test 1 (public)

Verdict: ACCEPTED

Test 2 (public)

Verdict: ACCEPTED

Test 3 (public)

Verdict: ACCEPTED

Test 4 (public)

Verdict: ACCEPTED

Test 5 (public)

Verdict: ACCEPTED

Test 6 (public)

Verdict: ACCEPTED

Test 7 (public)

Verdict: ACCEPTED

Test 8 (public)

Verdict: ACCEPTED

Test 9 (public)

Verdict: ACCEPTED

Test 10 (public)

Verdict: ACCEPTED