|
| 1 | +''' |
| 2 | +https://leetcode.com/problems/rotting-oranges/ |
| 3 | + |
| 4 | +In a given grid, each cell can have one of three values: |
| 5 | + |
| 6 | +the value 0 representing an empty cell; |
| 7 | +the value 1 representing a fresh orange; |
| 8 | +the value 2 representing a rotten orange. |
| 9 | +Every minute, any fresh orange that is adjacent (4-directionally) to a rotten orange becomes rotten. |
| 10 | + |
| 11 | +Return the minimum number of minutes that must elapse until no cell has a fresh orange. If this is impossible, return -1 instead. |
| 12 | + |
| 13 | +Runtime: 44 ms, faster than 98.53% of Python3 online submissions for Rotting Oranges. |
| 14 | +Memory Usage: 12.7 MB, less than 100.00% of Python3 online submissions for Rotting Oranges. |
| 15 | +''' |
| 16 | + |
| 17 | +from collections import deque |
| 18 | +class Solution: |
| 19 | + def orangesRotting(self, grid) -> int: |
| 20 | + # Setting up common used variable |
| 21 | + max_row = len(grid) |
| 22 | + max_col = len(grid[0]) |
| 23 | + rotten_oranges = [] |
| 24 | + |
| 25 | + # Put all of initial rottens orange in one array |
| 26 | + for row in range(max_row): |
| 27 | + for col in range(max_col): |
| 28 | + if grid[row][col] == 2: |
| 29 | + rotten_oranges.append((row,col)) |
| 30 | + # Hepler function. If the grid contain fresh orange, it will become rotten |
| 31 | + def spread_rotten(row,col): |
| 32 | + nonlocal grid, temp_rotten_oranges |
| 33 | + if grid[row][col] == 1: |
| 34 | + temp_rotten_oranges.append((row,col)) |
| 35 | + grid[row][col] = 2 |
| 36 | + |
| 37 | + # Each loop represent a minutes |
| 38 | + # In a loop, we use a temp array to store all of the rotten array got spreaded in that minutes |
| 39 | + # The loop only ends when the temp array is empty |
| 40 | + time = 0 |
| 41 | + while True: |
| 42 | + temp_rotten_oranges = [] |
| 43 | + for rotten_orange in rotten_oranges: |
| 44 | + row, col = rotten_orange |
| 45 | + if row > 0: |
| 46 | + spread_rotten(row-1, col) |
| 47 | + if col > 0: |
| 48 | + spread_rotten(row, col-1) |
| 49 | + if row < max_row - 1: |
| 50 | + spread_rotten(row+1, col) |
| 51 | + if col < max_col - 1: |
| 52 | + spread_rotten(row, col+1) |
| 53 | + if not temp_rotten_oranges: |
| 54 | + break |
| 55 | + rotten_oranges = temp_rotten_oranges.copy() |
| 56 | + time += 1 |
| 57 | + |
| 58 | + # Check the remaing array, return -1 if there's still a fresh orange left |
| 59 | + for row in range(max_row): |
| 60 | + for col in range(max_col): |
| 61 | + if grid[row][col] == 1: |
| 62 | + return -1 |
| 63 | + |
| 64 | + return time |
| 65 | + |
| 66 | + |
| 67 | + |
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