Monikulmio

def sign(x):
    if x > 0:
        return 1
    if x < 0:
        return -1
    return 0


height, width, cornerCount = (int(x) for x in input().split())
corners = [tuple(int(x) - 1 for x in input().split()) for _ in range(cornerCount)]

grid = [["#" for _ in range(width)] for _ in range(height)]

prev_y, prev_x = corners[-1]
for y, x in corners:
    dy = y - prev_y
    dx = x - prev_x
    char = "?"
    match (sign(dy), sign(dx)):
        case (1, 1) | (-1, -1):
            char = "\\"
        case (1, -1) | (-1, 1):
            char = "/"
        case (0, 1) | (0, -1):
            char = "="
        case (1, 0) | (-1, 0):
            char = "|"

    for t in range(1, max(abs(dy), abs(dx))):
        grid[prev_y + sign(dy) * t][prev_x + sign(dx) * t] = char

    grid[y][x] = "*"
    prev_y, prev_x = y, x


edge = (
    [(0, i) for i in range(width)]
    + [(-1, i) for i in range(width)]
    + [(i, 0) for i in range(height)]
    + [(i, -1) for i in range(height)]
)
edge = {(y, x) for (y, x) in edge if grid[y][x] == "#"}

visited: set[tuple[int, int]] = set(edge)
directions = [(0, 1), (0, -1), (1, 0), (-1, 0)]

while edge:
    y, x = edge.pop()
    grid[y][x] = "."
    for dy, dx in directions:
        new_pos = (y + dy, x + dx)
        if new_pos[0] not in range(height) or new_pos[1] not in range(width):
            continue
        if new_pos in visited:
            continue
        visited.add(new_pos)
        if grid[new_pos[0]][new_pos[1]] == "#":
            edge.add(new_pos)


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