from collections import deque
class Solution:
def numIslands(self, grid: List[List[str]]) -> int:
rowN = len(grid)
colN = len(grid[0])
dx = [0,0,-1,1]
dy = [-1,1,0,0]
count = 0
for i in range(rowN):
for j in range(colN):
if grid[i][j] == "1":
count += 1
q = deque()
grid[i][j] = "0"
q.append([i,j])
while q:
r, c = q.popleft()
for k in range(4):
x = r+dx[k]
y = c+dy[k]
if 0<=x<rowN and 0<=y<colN and grid[x][y] == "1":
q.append([x,y])
grid[x][y] = "0"
return count
easy하지~~~