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| 1 | +package p34xx |
| 2 | + |
| 3 | +import util.expect |
| 4 | +import kotlin.math.absoluteValue |
| 5 | + |
| 6 | +fun main() { |
| 7 | + class Solution { |
| 8 | + fun lenOfVDiagonal(grid: Array<IntArray>): Int { |
| 9 | + val directions = arrayOf( |
| 10 | + 1 to 1, |
| 11 | + 1 to -1, |
| 12 | + -1 to -1, |
| 13 | + -1 to 1, |
| 14 | + ) |
| 15 | + |
| 16 | + val initPos = hashSetOf<Pair<Int, Int>>() |
| 17 | + val cache = Array(grid.size) { r -> |
| 18 | + Array(grid[r].size) { c -> |
| 19 | + if (grid[r][c] == 1) { |
| 20 | + initPos.add(r to c) |
| 21 | + } |
| 22 | + |
| 23 | + Array(4) { intArrayOf(0, 0) } |
| 24 | + } |
| 25 | + } |
| 26 | + |
| 27 | + fun dfs(pos: Pair<Int, Int>, directionIndex: Int, turnCount: Int): Int { |
| 28 | + return if (cache[pos.first][pos.second][directionIndex][turnCount] > 0) { |
| 29 | + cache[pos.first][pos.second][directionIndex][turnCount] |
| 30 | + } else { |
| 31 | + var result = 0 |
| 32 | + |
| 33 | + val currentNum = grid[pos.first][pos.second] |
| 34 | + |
| 35 | + val forwardPos = pos.first + directions[directionIndex].first to pos.second + directions[directionIndex].second |
| 36 | + |
| 37 | + directions[directionIndex].let { |
| 38 | + grid.getOrNull(forwardPos.first)?.getOrNull(forwardPos.second) |
| 39 | + }?.takeIf { |
| 40 | + currentNum == 1 && it == 2 || (currentNum - it).absoluteValue == 2 |
| 41 | + }?.also { |
| 42 | + result = dfs(forwardPos, directionIndex, turnCount) |
| 43 | + } |
| 44 | + |
| 45 | + if (turnCount == 1 && currentNum != 1) { |
| 46 | + val turnDirectionIndex = (directionIndex + 1) % 4 |
| 47 | + val turnPos = pos.first + directions[turnDirectionIndex].first to pos.second + directions[turnDirectionIndex].second |
| 48 | + grid.getOrNull(turnPos.first)?.getOrNull(turnPos.second)?.takeIf { |
| 49 | + it != currentNum && it != 1 |
| 50 | + }?.also { |
| 51 | + result = maxOf(result, dfs(turnPos, turnDirectionIndex, 0)) |
| 52 | + } |
| 53 | + } |
| 54 | + |
| 55 | + result++ |
| 56 | + cache[pos.first][pos.second][directionIndex][turnCount] = result |
| 57 | + result |
| 58 | + } |
| 59 | + } |
| 60 | + |
| 61 | + return initPos.maxOfOrNull { pos -> |
| 62 | + (0 until 4).maxOf { directionIndex -> |
| 63 | + maxOf(dfs(pos, directionIndex, 0), dfs(pos, directionIndex, 1)) |
| 64 | + } |
| 65 | + } ?: 0 |
| 66 | + } |
| 67 | + } |
| 68 | + |
| 69 | + expect { |
| 70 | + Solution().lenOfVDiagonal( |
| 71 | + arrayOf( |
| 72 | + intArrayOf(1, 1, 2, 1, 0, 1, 1, 0, 0), |
| 73 | + intArrayOf(1, 0, 1, 2, 2, 0, 2, 1, 1), |
| 74 | + intArrayOf(1, 0, 2, 0, 2, 1, 1, 1, 1), |
| 75 | + ) |
| 76 | + ) |
| 77 | + } |
| 78 | +} |
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