[백준] 1743번 음식물 피하기

 

from collections import deque

def BFS(r, c):
    global N, M, field

    q = deque([(r, c)])
    field[r][c] = 0
    dx = [1, 0, -1, 0]
    dy = [0, 1, 0, -1]
    s = 1
    while q:
        y, x = q.popleft()
        for i in range(4):
            ny = y + dy[i]
            nx = x + dx[i]

            if 0 <= ny < N and 0 <= nx < M and field[ny][nx]:
                q.append((ny, nx))
                field[ny][nx] = 0

                s += 1
    return s



N, M, K = map(int, input().split())
field = [[0 for _ in range(M)] for _ in range(N)]
for i in range(K):
    r, c = map(int, input().split())
    field[r-1][c-1] = 1

size = -1
for i in range(N):
    for j in range(M):
        if field[i][j]:
            size = max(size, BFS(i, j))

print(size)

https://www.acmicpc.net/problem/1743

1743번: 음식물 피하기