40 lines
1.2 KiB
Kotlin
40 lines
1.2 KiB
Kotlin
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fun <A, B> product(xs: Sequence<A>, ys: Sequence<B>): Sequence<Pair<A, B>> =
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xs.flatMap { x -> ys.map { y -> x to y } }
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fun <A, B> product(xs: Iterable<A>, ys: Iterable<B>): Sequence<Pair<A, B>> =
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product(xs.asSequence(), ys.asSequence())
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class Solution {
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fun BFS(grid: Array<IntArray>, coords: Pair<Int, Int>): Int {
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val queue = ArrayDeque<Pair<Int, Int>>()
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queue.addLast(coords)
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var size = 0
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while (!queue.isEmpty()) {
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val (y, x) = queue.removeFirst()
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if (grid[y][x] != 1) {
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continue
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}
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for ((dy, dx) in sequenceOf(0 to 1, 1 to 0, 0 to -1, -1 to 0)) {
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if (!(y + dy in grid.indices) || !(x + dx in grid[y + dy].indices)) {
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continue
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} else if (grid[y + dy][x + dx] != 1) {
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continue
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}
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queue.addLast(y + dy to x + dx)
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}
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// mark it as done
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grid[y][x] = 0
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size++
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}
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return size
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}
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fun maxAreaOfIsland(grid: Array<IntArray>): Int =
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product(grid.indices, grid.first().indices).map { BFS(grid, it) }.max() ?: 0
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}
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