結果

問題 No.1885 Flat Permutation
コンテスト
ユーザー 箱星
提出日時 2022-09-11 19:16:41
言語 Kotlin
(2.1.0)
結果
AC  
実行時間 1,331 ms / 2,000 ms
コード長 3,299 bytes
コンパイル時間 17,806 ms
コンパイル使用メモリ 446,312 KB
実行使用メモリ 107,572 KB
最終ジャッジ日時 2024-11-28 09:24:10
合計ジャッジ時間 49,825 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge3
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
sample AC * 4
other AC * 43
権限があれば一括ダウンロードができます

ソースコード

diff # 

import java.io.PrintWriter
import java.util.*
import kotlin.math.*

fun PrintWriter.solve() {
    val n = nextInt()
    val _x = nextInt()
    val _y = nextInt()
    val x = minOf(_x, _y)
    val y = maxOf(_x, _y)
    val a = if (x == 1) 1 else x + 1
    val b = if (y == n) n else y - 1
    val l = b - a
    val memo = mutableMapOf<Int, ModInt>()
    fun f(l: Int): ModInt {
        if (l < 0) {
            return ModInt(0)
        }
        if (l <= 2) {
            return ModInt(1)
        }
        if (memo.containsKey(l)) {
            return memo[l]!!
        }
        val ret = f(l - 1) + f(l - 3)
        memo[l] = ret
        return ret
    }
    println(f(l))
}

// region ModInt
class ModInt(x: Long) {
    companion object {
        const val MOD = 998244353L
        //const val MOD = 1000000007L
    }

    constructor(y: Int) : this(y.toLong())

    val x = (x % MOD + MOD) % MOD

    operator fun plus(other: ModInt): ModInt {
        return ModInt(x + other.x)
    }

    operator fun minus(other: ModInt): ModInt {
        return ModInt(x - other.x)
    }

    operator fun times(other: ModInt): ModInt {
        return ModInt(x * other.x)
    }

    operator fun div(other: ModInt): ModInt {
        return this * other.inv()
    }

    fun pow(exp: Long): ModInt {
        if (exp == 0L) return ModInt(1L)
        var a = pow(exp shr 1)
        a *= a
        if (exp and 1L == 0L) return a
        return this * a
    }

    fun inv(): ModInt {
        return this.pow(MOD - 2)
    }

    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (javaClass != other?.javaClass) return false

        other as ModInt

        if (x != other.x) return false

        return true
    }

    override fun hashCode(): Int {
        return x.hashCode()
    }

    override fun toString(): String {
        return "$x"
    }
}

class ModIntArray(n: Int) {
    private val a = LongArray(n) { 0L }

    constructor(n: Int, init: (Int) -> ModInt) : this(n) {
        for (i in 0 until n) {
            a[i] = init(i).x
        }
    }

    operator fun set(i: Int, x: ModInt) {
        a[i] = x.x
    }

    operator fun get(i: Int): ModInt {
        return ModInt(a[i])
    }

    fun joinToString(s: String = ", "): String {
        return a.joinToString(s)
    }
}

fun Long.toModInt() = ModInt(this)

fun Int.toModInt() = ModInt(this)

fun binomSimple(n: Long, k: Long): ModInt {
    var numer = ModInt(1)
    var denom = ModInt(1)
    for (i in 0 until k) {
        numer *= ModInt(n - i)
        denom *= ModInt(k - i)
    }
    return numer / denom
}
// endregion

fun main() {
    Thread(null, {
        val writer = PrintWriter(System.out, false)
        writer.solve()
        writer.flush()
    }, "solve", abs(1L.shl(26)))
        .apply { setUncaughtExceptionHandler { _, e -> e.printStackTrace(); kotlin.system.exitProcess(1) } }
        .apply { start() }.join()
}

// region Scanner
private var st = StringTokenizer("")
private val br = System.`in`.bufferedReader()

fun next(): String {
    while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())
    return st.nextToken()
}

fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextLine() = br.readLine()
fun nextDouble() = next().toDouble()
// endregion
0