标签：sub elements pre red tput ges square for col
Given a 2D grid of 0s and 1s, return the number of elements in the largest square subgrid that has all 1s on its border, or 0 if such a subgrid doesn‘t exist in the grid.
Example 1:
Input: grid = [[1,1,1],[1,0,1],[1,1,1]] Output: 9
Example 2:
Input: grid = [[1,1,0,0]] Output: 1
1 class Solution { 2 public int largest1BorderedSquare(int[][] A) { 3 int m = A.length, n = A[0].length; 4 int[][] left = new int[m][n], top = new int[m][n]; 5 for (int i = 0; i < m; ++i) { 6 for (int j = 0; j < n; ++j) { 7 if (A[i][j] > 0) { 8 left[i][j] = j > 0 ? left[i][j - 1] + 1 : 1; 9 top[i][j] = i > 0 ? top[i - 1][j] + 1 : 1; 10 } 11 } 12 } 13 for (int l = Math.min(m, n); l > 0; --l) 14 for (int i = 0; i < m - l + 1; ++i) 15 for (int j = 0; j < n - l + 1; ++j) 16 if (top[i + l - 1][j] >= l && 17 top[i + l - 1][j + l - 1] >= l && 18 left[i][j + l - 1] >= l && 19 left[i + l - 1][j + l - 1] >= l) 20 return l * l; 21 return 0; 22 } 23 }
标签：sub elements pre red tput ges square for col
原文地址：https://www.cnblogs.com/beiyeqingteng/p/12251756.html
