2906. Construct Product Matrix

2906. Construct Product Matrix/Program.cs

@@ -1,2 +1,74 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+static string FormatMatrix(int[][] matrix)
+{
+    var rows = new string[matrix.Length];
+    for (var i = 0; i < matrix.Length; i++)
+        rows[i] = "[" + string.Join(",", matrix[i]) + "]";
+    return "[" + string.Join(",", rows) + "]";
+}
+
+var sol = new Solution();
+
+var cases = new (int[][] input, string expected)[]
+{
+    (
+        new[]
+        {
+            new[] { 1, 2 },
+            new[] { 3, 4 }
+        },
+        "[[24,12],[8,6]]"
+    ),
+    (
+        new[]
+        {
+            new[] { 12345 },
+            new[] { 2 },
+            new[] { 1 }
+        },
+        "[[2],[0],[0]]"
+    ),
+    (
+        new[]
+        {
+            new[] { 4, 8, 8 },
+            new[] { 6, 2, 5 },
+            new[] { 7, 3, 7 },
+            new[] { 6, 3, 5 }
+        },
+        "[[3525,7935,7935],[6465,7050,2820],[7305,585,7305],[6465,585,2820]]"
+    ),
+    (
+        new[]
+        {
+            new[] { 4, 3, 9 },
+            new[] { 3, 9, 10 },
+            new[] { 9, 7, 8 },
+            new[] { 8, 4, 7 },
+            new[] { 6, 1, 3 }
+        },
+        "[[3255,225,75],[225,75,11178],[75,1860,7800],[7800,3255,1860],[6285,675,225]]"
+    ),
+    (
+        new[]
+        {
+            new []{1,2,2},
+            new []{1,4,3}
+        },
+        "[[48,24,24],[48,12,16]]"
+    ),
+    (
+        new[]
+        {
+            new[] { 414750857 },
+            new[] { 449145368 },
+            new[] { 767292749 }
+        },
+        "[[1462],[3103],[9436]]"
+    )
+};
+
+foreach (var (input, expected) in cases)
+{
+    var actual = sol.ConstructProductMatrix(input);
+    Console.WriteLine($"{FormatMatrix(input)} -> {FormatMatrix(actual)} (expected: {expected})");
+}

2906. Construct Product Matrix/Solution.cs

@@ -0,0 +1,80 @@
+public class Solution
+{
+    struct MulInfo
+    {
+        public long Left;
+        public long Right;
+    }
+
+
+    public int[][] ConstructProductMatrix(int[][] grid)
+    {
+        var mod = 12345;
+        var table = new MulInfo[grid.Length][];
+
+        var lastRow = grid.Length - 1;
+        var lastCol = grid[0].Length - 1;
+
+        // прямой проход
+        for (var i = 0; i < grid.Length; i++)
+        {
+            table[i] = new MulInfo[grid[i].Length];
+            for (var j = 0; j < grid[i].Length; j++)
+            {
+                if (j == 0 && i == 0)
+                {
+                    table[i][j].Left = grid[i][j] % mod;
+                }
+                else if (j > 0)
+                {
+                    table[i][j].Left = table[i][j - 1].Left * grid[i][j] % mod;
+                }
+                else if (i > 0)
+                {
+                    table[i][j].Left = table[i - 1][lastCol].Left * grid[i][j];
+                    table[i][j].Left %= mod;
+                }
+
+            }
+        }
+
+        // обратный проход
+        for (var i = lastRow; i >= 0; i--)
+        {
+            for (var j = lastCol; j >= 0; j--)
+            {
+                if (j == lastCol && i == lastRow)
+                {
+                    table[i][j].Right = grid[i][j] % mod;
+                }
+                else if (j < lastCol)
+                {
+                    table[i][j].Right = table[i][j + 1].Right * grid[i][j] % mod;
+                }
+                else if (i < lastRow)
+                {
+                    table[i][j].Right = table[i + 1][0].Right * grid[i][j] % mod;
+                }
+                
+                var left = 1L;
+                var right = 1L;
+                if (i == 0 && j == 0)
+                    left = 1;
+                else if (j > 0)
+                    left = table[i][j - 1].Left;
+                else if (i > 0)
+                    left = table[i - 1][lastCol].Left;
+
+                if (i == lastRow && j == lastCol)
+                    right = 1;
+                else if (j < lastCol)
+                    right = table[i][j + 1].Right;
+                else if (i < lastRow)
+                    right = table[i + 1][0].Right;
+                grid[i][j] = (int)(left * right % mod);
+            }
+        }
+
+        return grid;
+    }
+}