kt: add «2290. Minimum Obstacle Removal to Reach Corner»

URL:	https://leetcode.com/problems/minimum-obstacle-removal-to-reach-corner/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/minimum-obstacle-removal-to-reach-corner.kt

@@ -0,0 +1,54 @@
+class Solution {
+    private data class Position(val x: Int, val y: Int) {
+        operator fun plus(rhs: Position): Position = Position(x + rhs.x, y + rhs.y)
+    }
+
+    companion object {
+        private val DIRECTIONS =
+            listOf(
+                Position(0, 1),
+                Position(0, -1),
+                Position(1, 0),
+                Position(-1, 0),
+            )
+    }
+
+    private fun isValid(
+        grid: Array<IntArray>,
+        p: Position,
+    ): Boolean =
+        (
+            p.y >= 0 && p.y < grid.size && p.x >= 0 && p.x < grid[p.y].size
+        )
+
+    fun minimumObstacles(grid: Array<IntArray>): Int {
+        val (rows, cols) = grid.size to grid[0].size
+
+        val dp = Array(rows) { IntArray(cols) { Int.MAX_VALUE } }
+        dp[0][0] = 0
+
+        val deque = ArrayDeque<Pair<Position, Int>>()
+        deque.addLast(Position(0, 0) to 0)
+
+        while (!deque.isEmpty()) {
+            val (position, obstacles) = deque.removeFirst()
+
+            DIRECTIONS.forEach { dir ->
+                val next = position + dir
+                if (!isValid(grid, next) || dp[next.y][next.x] != Int.MAX_VALUE) {
+                    return@forEach
+                }
+
+                if (grid[next.y][next.x] == 1) {
+                    dp[next.y][next.x] = obstacles + 1
+                    deque.addLast(next to obstacles + 1)
+                } else {
+                    dp[next.y][next.x] = obstacles
+                    deque.addFirst(next to obstacles)
+                }
+            }
+        }
+
+        return dp[rows - 1][cols - 1]
+    }
+}