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Solution.cs
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68 lines (67 loc) · 1.69 KB
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public class Solution
{
public int LargestMagicSquare(int[][] grid)
{
int n = grid.Length, m = grid[0].Length;
for (int k = Math.Min(n, m); k > 0; k--)
{
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
if (IsMagicSquare(i, j, k, grid)) return k;
}
}
}
return 0;
}
bool IsMagicSquare(int x, int y, int k, int[][] grid)
{
int n = grid.Length, m = grid[0].Length;
if (x + k > n || y + k > m) return false;
long sum = 0;
for (int i = x; i < x + k; i++)
{
for (int j = y; j < y + k; j++)
{
sum += grid[i][j];
}
}
if (sum % k != 0) return false;
long target = sum / k;
// check row
for (int i = x; i < x + k; i++)
{
sum = 0;
for (int j = y; j < y + k; j++)
{
sum += grid[i][j];
}
if (sum != target) return false;
}
// check col
for (int j = y; j < y + k; j++)
{
sum = 0;
for (int i = x; i < x + k; i++)
{
sum += grid[i][j];
}
if (sum != target) return false;
}
// check dialog
sum = 0;
for (int i = 0; i < k; i++)
{
sum += grid[x + i][y + i];
}
if (sum != target) return false;
sum = 0;
for (int i = 0; i < k; i++)
{
sum += grid[x + i][y + k - 1 - i];
}
if (sum != target) return false;
return true;
}
}