kt: add «2684. Maximum Number of Moves in a Grid»

URL:	https://leetcode.com/problems/maximum-number-of-moves-in-a-grid/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/maximum-number-of-moves-in-a-grid.kt

@@ -0,0 +1,38 @@
+class Solution {
+    fun <A, B> product(
+        xs: Sequence<A>,
+        ys: Sequence<B>,
+    ): Sequence<Pair<A, B>> = xs.flatMap { x -> ys.map { y -> x to y } }
+
+    fun <A, B, C> product(
+        xs: Sequence<A>,
+        ys: Sequence<B>,
+        zs: Sequence<C>,
+    ): Sequence<Triple<A, B, C>> = xs.flatMap { x -> ys.flatMap { y -> zs.map { z -> Triple(x, y, z) } } }
+
+    fun <A, B> product(
+        xs: Iterable<A>,
+        ys: Iterable<B>,
+    ): Sequence<Pair<A, B>> = product(xs.asSequence(), ys.asSequence())
+
+    fun <A, B, C> product(
+        xs: Iterable<A>,
+        ys: Iterable<B>,
+        zs: Iterable<C>,
+    ): Sequence<Triple<A, B, C>> = product(xs.asSequence(), ys.asSequence(), zs.asSequence())
+
+    fun maxMoves(grid: Array<IntArray>): Int {
+        val dp = Array(grid.size) { IntArray(grid[0].size) }
+
+        product(grid[0].indices.reversed().drop(1), grid.indices, -1..1).filter {
+                (x, y, dy) ->
+            y + dy >= 0 && y + dy < dp.size && grid[y][x] < grid[y + dy][x + 1]
+        }.forEach { (x, y, dy) ->
+            dp[y][x] = listOf(dp[y][x], 1 + dp[y + dy][x + 1]).max()
+        }
+
+        return dp.indices.maxOf { y ->
+            dp[y][0]
+        }
+    }
+}