diff options
Diffstat (limited to 'min_num_days_disconnect_island.py')
-rw-r--r-- | min_num_days_disconnect_island.py | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/min_num_days_disconnect_island.py b/min_num_days_disconnect_island.py new file mode 100644 index 0000000..14dfd44 --- /dev/null +++ b/min_num_days_disconnect_island.py @@ -0,0 +1,62 @@ +# 1568. Minimum Number of Days to Disconnect Island + +""" +you are given an 'm * n' binary grid where 1 repansents land and 0 repansents +water. an island is a maximal 4 directionally horizontal or vertical +connected group of 1's. the grid is said to be connected if we have exactly +one island otherwise it is disconnected. in one day, we are allowed to change +any single land cell 1 into a water cell 0. return the minimum number of days +to disconnect the grid. +""" + + +class Solution(object): + def minDays(self, grid): + """ + :type grid: List[List[int]] + :rtype: int + """ + cnt = 0 + for i in range(len(grid)): + for j in range(len(grid[0])): + if grid[i][j]: + cnt += 1 + root = (i, j) + if cnt <= 1: + return cnt + vis, low, time, ans = {root}, {}, {}, [] + + def articulation_points(curr, parent): + low[curr] = time[curr] = len(vis) + children = 0 + i, j = curr + for x, y in [(i + 1, j), (i - 1, j), (i, j + 1), (i, j - 1)]: + if (x, y) == parent: + continue + if 0 <= x < len(grid) and 0 <= y < len(grid[0]) and grid[x][y]: + if (x, y) not in vis: + vis.add((x, y)) + articulation_points((x, y), curr) + low[curr] = min(low[curr], low[(x, y)]) + children += 1 + if low[(x, y)] >= time[(curr)] and parent != (-1, -1): + ans.append([i, j]) + else: + low[curr] = min(low[curr], time[(x, y)]) + + if parent == (-1, -1) and children > 1: + ans.append([x, y]) + + articulation_points(root, (-1, -1)) + if len(vis) != cnt: + return 0 + elif ans: + return 1 + else: + return 2 + + +if __name__ == "__main__": + obj = Solution() + print(obj.minDays(grid=[[0, 1, 1, 0], [0, 1, 1, 0], [0, 0, 0, 0]])) + print(obj.minDays(grid=[[1, 1]])) |