{ "data": { "question": { "questionId": "769", "questionFrontendId": "764", "categoryTitle": "Algorithms", "boundTopicId": 1884, "title": "Largest Plus Sign", "titleSlug": "largest-plus-sign", "content": "
You are given an integer n
. You have an n x n
binary grid grid
with all values initially 1
's except for some indices given in the array mines
. The ith
element of the array mines
is defined as mines[i] = [xi, yi]
where grid[xi][yi] == 0
.
Return the order of the largest axis-aligned plus sign of 1's contained in grid
. If there is none, return 0
.
An axis-aligned plus sign of 1
's of order k
has some center grid[r][c] == 1
along with four arms of length k - 1
going up, down, left, and right, and made of 1
's. Note that there could be 0
's or 1
's beyond the arms of the plus sign, only the relevant area of the plus sign is checked for 1
's.
\n
Example 1:
\n\n\nInput: n = 5, mines = [[4,2]]\nOutput: 2\nExplanation: In the above grid, the largest plus sign can only be of order 2. One of them is shown.\n\n\n
Example 2:
\n\n\nInput: n = 1, mines = [[0,0]]\nOutput: 0\nExplanation: There is no plus sign, so return 0.\n\n\n
\n
Constraints:
\n\n1 <= n <= 500
1 <= mines.length <= 5000
0 <= xi, yi < n
(xi, yi)
are unique.在一个 n x n
的矩阵 grid
中,除了在数组 mines
中给出的元素为 0
,其他每个元素都为 1
。mines[i] = [xi, yi]
表示 grid[xi][yi] == 0
返回 grid
中包含 1
的最大的 轴对齐 加号标志的阶数 。如果未找到加号标志,则返回 0
。
一个 k
阶由 1
组成的 “轴对称”加号标志 具有中心网格 grid[r][c] == 1
,以及4个从中心向上、向下、向左、向右延伸,长度为 k-1
,由 1
组成的臂。注意,只有加号标志的所有网格要求为 1
,别的网格可能为 0
也可能为 1
。
\n\n
示例 1:
\n\n\n\n\n输入: n = 5, mines = [[4, 2]]\n输出: 2\n解释: 在上面的网格中,最大加号标志的阶只能是2。一个标志已在图中标出。\n\n\n
示例 2:
\n\n\n\n\n输入: n = 1, mines = [[0, 0]]\n输出: 0\n解释: 没有加号标志,返回 0 。\n\n\n
\n\n
提示:
\n\n1 <= n <= 500
1 <= mines.length <= 5000
0 <= xi, yi < n
(xi, yi)
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out-of-bounds<\\/code>\\u548c
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