Day i do not know

542. 01 Matrix/Solution.cs

@@ -0,0 +1,35 @@
+namespace _542._01_Matrix;
+
+public class Solution
+{
+    public int[][] UpdateMatrix(int[][] mat)
+    {
+        bool hasChanges = true;
+        while(hasChanges)
+        {
+            hasChanges = false;
+            for (int y = 0; y < mat.Length; y++)
+            {
+                for (int x = 0; x < mat[y].Length; x++)
+                {
+                    if (mat[y][x] == 0)
+                        continue;
+                    int min = int.MaxValue;
+                    for (int i = 1; i < 9; i += 2)
+                    {
+                        int newY = i / 3 + y - 1;
+                        int newX = i % 3 + x - 1;
+                        if (newY >= 0 && newY < mat.Length && newX >= 0 && newX < mat[newY].Length)
+                        {
+                            min = Math.Min(min, mat[newY][newX]);
+                        }
+                    }
+                    if(mat[y][x] != min + 1)
+                        hasChanges = true;
+                    mat[y][x] = min + 1;
+                }
+            }
+        }
+        return mat;
+    }
+}