LC 0723 [M] Candy Crush - ALawliet/algorithms GitHub Wiki

https://www.youtube.com/watch?v=p4jExm5Zf6Q&ab_channel=babybear4812

• check 3 in a row
• keep done/stable state
• tag with - numbers
• crush down is like move zeroes but we move the positive numbers down

class Solution:
    def candyCrush(self, board: List[List[int]]) -> List[List[int]]:
        if not board:
            return board
        
        done = True
        #STEP 1: CRUSH ROWS
        for r in range(len(board)):
            for c in range(len(board[r]) - 2): # stop at 3rd to last
                num1 = abs(board[r][c])
                num2 = abs(board[r][c+1])
                num3 = abs(board[r][c+2])
                if num1 == num2 and num2 == num3 and num1 != 0:
                    board[r][c] = -num1
                    board[r][c+1] = -num2
                    board[r][c+2] = -num3
                    done = False
        
        #STEP 2: CRUSH COLS
        for c in range(len(board[0])):
            for r in range(len(board) - 2):
                num1 = abs(board[r][c])
                num2 = abs(board[r+1][c])
                num3 = abs(board[r+2][c])
                if num1 == num2 and num2 == num3 and num1 != 0:
                    board[r][c] = -num1
                    board[r+1][c] = -num2
                    board[r+2][c] = -num3
                    done = False
        
        #STEP 3: GRAVITY
        if not done:
            for c in range(len(board[0])):
                # move all positive numbers down
                idx = len(board) - 1 # first replacement
                for r in range(len(board) - 1, -1, -1): # bottom up
                    if board[r][c] > 0:
                        board[idx][c] = board[r][c] # crush down
                        idx -= 1 # move up (everything below here needs to stay because it's dropped, but we work up)

                # put zeroes in for missing prices
                for r in range(idx, -1, -1):
                    board[r][c] = 0

        return board if done else self.candyCrush(board)