{ "data": { "question": { "questionId": "821", "questionFrontendId": "803", "boundTopicId": null, "title": "Bricks Falling When Hit", "titleSlug": "bricks-falling-when-hit", "content": "
You are given an m x n
binary grid
, where each 1
represents a brick and 0
represents an empty space. A brick is stable if:
You are also given an array hits
, which is a sequence of erasures we want to apply. Each time we want to erase the brick at the location hits[i] = (rowi, coli)
. The brick on that location (if it exists) will disappear. Some other bricks may no longer be stable because of that erasure and will fall. Once a brick falls, it is immediately erased from the grid
(i.e., it does not land on other stable bricks).
Return an array result
, where each result[i]
is the number of bricks that will fall after the ith
erasure is applied.
Note that an erasure may refer to a location with no brick, and if it does, no bricks drop.
\n\n\n
Example 1:
\n\n\nInput: grid = [[1,0,0,0],[1,1,1,0]], hits = [[1,0]]\nOutput: [2]\nExplanation: Starting with the grid:\n[[1,0,0,0],\n [1,1,1,0]]\nWe erase the underlined brick at (1,0), resulting in the grid:\n[[1,0,0,0],\n [0,1,1,0]]\nThe two underlined bricks are no longer stable as they are no longer connected to the top nor adjacent to another stable brick, so they will fall. The resulting grid is:\n[[1,0,0,0],\n [0,0,0,0]]\nHence the result is [2].\n\n\n
Example 2:
\n\n\nInput: grid = [[1,0,0,0],[1,1,0,0]], hits = [[1,1],[1,0]]\nOutput: [0,0]\nExplanation: Starting with the grid:\n[[1,0,0,0],\n [1,1,0,0]]\nWe erase the underlined brick at (1,1), resulting in the grid:\n[[1,0,0,0],\n [1,0,0,0]]\nAll remaining bricks are still stable, so no bricks fall. The grid remains the same:\n[[1,0,0,0],\n [1,0,0,0]]\nNext, we erase the underlined brick at (1,0), resulting in the grid:\n[[1,0,0,0],\n [0,0,0,0]]\nOnce again, all remaining bricks are still stable, so no bricks fall.\nHence the result is [0,0].\n\n\n
\n
Constraints:
\n\nm == grid.length
n == grid[i].length
1 <= m, n <= 200
grid[i][j]
is 0
or 1
.1 <= hits.length <= 4 * 104
hits[i].length == 2
0 <= xi <= m - 1
0 <= yi <= n - 1
(xi, yi)
are unique.Compiled with clang 11
using the latest C++ 17 standard.
Your code is compiled with level two optimization (-O2
). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
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