結果

問題 No.1507 Road Blocked
ユーザー yakamotoyakamoto
提出日時 2021-05-14 22:35:09
言語 Kotlin
(1.9.23)
結果
AC  
実行時間 606 ms / 2,000 ms
コード長 5,012 bytes
コンパイル時間 17,405 ms
コンパイル使用メモリ 462,860 KB
実行使用メモリ 84,464 KB
最終ジャッジ日時 2024-04-10 01:14:02
合計ジャッジ時間 37,712 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（β）

テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 276 ms
54,332 KB
testcase_01 AC 278 ms
54,428 KB
testcase_02 AC 276 ms
54,424 KB
testcase_03 AC 559 ms
84,088 KB
testcase_04 AC 603 ms
84,188 KB
testcase_05 AC 598 ms
84,288 KB
testcase_06 AC 590 ms
83,956 KB
testcase_07 AC 578 ms
84,128 KB
testcase_08 AC 580 ms
84,256 KB
testcase_09 AC 586 ms
83,904 KB
testcase_10 AC 584 ms
84,120 KB
testcase_11 AC 590 ms
84,272 KB
testcase_12 AC 592 ms
84,156 KB
testcase_13 AC 592 ms
84,372 KB
testcase_14 AC 593 ms
84,252 KB
testcase_15 AC 576 ms
84,000 KB
testcase_16 AC 585 ms
84,368 KB
testcase_17 AC 591 ms
84,088 KB
testcase_18 AC 588 ms
84,160 KB
testcase_19 AC 593 ms
84,288 KB
testcase_20 AC 606 ms
84,424 KB
testcase_21 AC 593 ms
84,328 KB
testcase_22 AC 594 ms
84,464 KB
testcase_23 AC 591 ms
84,204 KB
testcase_24 AC 593 ms
84,176 KB
testcase_25 AC 594 ms
84,128 KB
testcase_26 AC 597 ms
84,148 KB
testcase_27 AC 595 ms
84,276 KB
testcase_28 AC 590 ms
84,284 KB
testcase_29 AC 587 ms
84,144 KB
testcase_30 AC 576 ms
84,120 KB
testcase_31 AC 582 ms
83,944 KB
testcase_32 AC 582 ms
84,092 KB
権限があれば一括ダウンロードができます
コンパイルメッセージ
Main.kt:95:9: warning: the value 'u' assigned to 'var v: Int defined in Solver.solve' is never used
        v = u
        ^
Main.kt:200:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun debug(a: LongArray) {
          ^
Main.kt:204:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun debug(a: IntArray) {
          ^
Main.kt:208:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun debug(a: BooleanArray) {
          ^
Main.kt:212:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun toString(a: BooleanArray) = run{a.map { if (it) 1 else 0 }.joinToString("")}
          ^
Main.kt:214:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun debugDim(A: Array<LongArray>) {
          ^
Main.kt:221:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun debugDim(A: Array<IntArray>) {
          ^
Main.kt:228:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun debugDim(A: Array<BooleanArray>) {
          ^
Main.kt:245:11: warning: expected performance impact from inlining is insignificant. Inlining works best for functions with parameters of functional types
  private inline fun assert(b: Boolean) = run{if (!b) throw AssertionError()}
          ^

ソースコード

diff # 

import java.io.BufferedReader
import java.io.InputStream
import java.io.InputStreamReader
import java.lang.AssertionError
import java.util.*
import kotlin.math.abs
import kotlin.math.max
import kotlin.math.min

val MOD = 998_244_353

fun packUGraph(n: Int, from: IntArray, to: IntArray): Array<IntArray> {
  val p = IntArray(n)
  val m = from.size
  for (i in 0 until m) {
    ++p[from[i]]
    ++p[to[i]]
  }
  val g = Array(n){IntArray(p[it])}
  for (i in 0 until m) {
    g[from[i]][--p[from[i]]] = to[i]
    g[to[i]][--p[to[i]]] = from[i]
  }
  return g
}
/**
 * (dist, parent, queue)
 * @param rt ルートノードを指定する。nullの場合は全ノード辿るまで繰り返す
 */
fun traceBfs(g: Array<IntArray>, rt: Int? = 0): Array<IntArray> {
  val n = g.size
  val q = IntArray(n)
  val d = IntArray(n)
  val p = IntArray(n){-2}
  var h = 0
  var t = 0

  fun bfs(rt: Int) {
    p[rt] = -1
    q[t++] = rt
    d[rt] = 0
    while (h < t) {
      val v = q[h++]
      for (i in g[v].indices) { // List<Int>に変更したときこちらの方法でないとiterator生成して遅くなる
        val u = g[v][i]
        if (p[u] == -2) {
          p[u] = v
          q[t++] = u
          d[u] = d[v] + 1
        }
      }
    }
  }

  if (rt != null) {
    bfs(rt)
  } else {
    for (v in 0 until n) {
      if (p[v] != -2) continue
      bfs(v)
    }
  }
  return arrayOf(d, p, q)
}
fun powMod(a: Long, n: Long, mod: Int): Long {
  if (n == 0L) return 1
  val res = powMod(a * a % mod, n / 2, mod)
  return if (n % 2 == 1L) res * a % mod else res
}
class Solver(stream: InputStream, private val out: java.io.PrintWriter) {
  private val reader = BufferedReader(InputStreamReader(stream), 32768)

  fun solve() {
    val N = ni()
    val (from, to) = na2(N - 1, -1)
    val g = packUGraph(N, from, to)
    val (_, par, que) = traceBfs(g)
    val dp = LongArray(N)
    for (i in N - 1 downTo 0) {
      val v = que[i]
      dp[v]++
      for (u in g[v]) {
        if (u == par[v]) continue
        dp[v] += dp[u]
      }
    }
    debug(dp)

    var cnt = 0L
    for (i in 0 until N - 1) {
      var v = from[i] // 親
      var u = to[i]
      if (par[v] == u) {
        val t = v
        v = u
        u = t
      }
      val n = dp[u] // 子供側
      val m = N - n
      cnt = (cnt + n*(n - 1)/2 + m*(m - 1)/2)%MOD
//      debug{"$n $m $cnt"}
    }
    debug{"$cnt"}
    val invn1 = powMod(N.toLong()-1, MOD.toLong()-2, MOD)
    val invn = powMod(N.toLong(), MOD.toLong()-2, MOD)
    val ans = cnt *invn1% MOD *invn%MOD *invn1%MOD *2%MOD // q = (n-1)*n*(n-1)/2
    out.println(ans)
  }













































  private val isDebug = try {
    // なんか本番でエラーでる
    System.getenv("MY_DEBUG") != null
  } catch (t: Throwable) {
    false
  }

  private var tokenizer: StringTokenizer? = null
  private fun next(): String {
    while (tokenizer == null || !tokenizer!!.hasMoreTokens()) {
      tokenizer = StringTokenizer(reader.readLine())
    }
    return tokenizer!!.nextToken()
  }

  private fun ni() = next().toInt()
  private fun nl() = next().toLong()
  private fun ns() = next()
  private fun na(n: Int, offset: Int = 0): IntArray {
    return IntArray(n) { ni() + offset }
  }
  private fun nal(n: Int, offset: Int = 0): LongArray {
    val res = LongArray(n)
    for (i in 0 until n) {
      res[i] = nl() + offset
    }
    return res
  }

  private fun na2(n: Int, offset: Int = 0): Array<IntArray> {
    val a  = Array(2){IntArray(n)}
    for (i in 0 until n) {
      for (e in a) {
        e[i] = ni() + offset
      }
    }
    return a
  }

  private inline fun debug(msg: () -> String) {
    if (isDebug) System.err.println(msg())
  }

  /**
   * コーナーケースでエラー出たりするので、debug(dp[1])のように添え字付きの場合はdebug{}をつかうこと
   */
  private inline fun debug(a: LongArray) {
    debug { a.joinToString(" ") }
  }

  private inline fun debug(a: IntArray) {
    debug { a.joinToString(" ") }
  }

  private inline fun debug(a: BooleanArray) {
    debug { toString(a) }
  }

  private inline fun toString(a: BooleanArray) = run{a.map { if (it) 1 else 0 }.joinToString("")}

  private inline fun debugDim(A: Array<LongArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }
  private inline fun debugDim(A: Array<IntArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }
  private inline fun debugDim(A: Array<BooleanArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }

  /**
   * 勝手にimport消されるのを防ぎたい
   */
  private fun hoge() {
    min(1, 2)
    max(1, 2)
    abs(-10)
  }

  private inline fun assert(b: Boolean) = run{if (!b) throw AssertionError()}
  private inline fun assert(b: Boolean, f: () -> String) = run{if (!b) throw AssertionError(f())}
}

fun main() {
  val out = java.io.PrintWriter(System.out)
  Solver(System.`in`, out).solve()
  out.flush()
}
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