# Clean O(MN) solution each iteration

• ``````class Solution(object):
def candyCrush(self, board):
def scanHorizontally(to_crush):
starts = [0] * M # Scan horizontally from each row starting from index 0
for i in range(M):
while starts[i] < N:
cnt = 0
start = starts[i]
while starts[i] < N:
if board[i][start] == 0 or board[i][start] != board[i][starts[i]]:
break
cnt += 1
starts[i] += 1
if cnt == 0: # Skip 0
starts[i] += 1
elif cnt >= 3:
for k in range(start, starts[i]):
def scanVertically(to_crush):
starts = [0] * N # Scan horizontally from each column starting from index 0
for j in range(N):
while starts[j] < M:
cnt = 0
start = starts[j]
while starts[j] < M:
if board[start][j] == 0 or board[start][j] != board[starts[j]][j]:
break
cnt += 1
starts[j] += 1
if cnt == 0: # Skip 0
starts[j] += 1
elif cnt >= 3:
for k in range(start, starts[j]):
def crush(to_crush):
for i, j in to_crush:
board[i][j] = 0
def drop(): # Similar to move zeros
for j in range(N):
idx = M - 1
for i in range(M - 1, -1, -1):
if board[i][j] != 0:
board[idx][j] = board[i][j]
idx -= 1
for i in range(idx, -1, -1):
board[i][j] = 0

M = len(board)
N = len(board[0])
while True:
to_crush = set()
scanHorizontally(to_crush)
scanVertically(to_crush)
if not to_crush:
break
crush(to_crush)
drop()
return board
``````

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