結果

問題 No.1424 Ultrapalindrome
コンテスト
ユーザー yakamoto
提出日時 2021-03-12 21:50:28
言語 Kotlin
(2.1.0)
結果
AC  
実行時間 595 ms / 2,000 ms
コード長 4,953 bytes
コンパイル時間 18,472 ms
コンパイル使用メモリ 471,040 KB
実行使用メモリ 108,616 KB
最終ジャッジ日時 2024-10-14 16:12:37
合計ジャッジ時間 32,569 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge5
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 29
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:214:11: 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:218:11: 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:222:11: 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:226:11: 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: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<LongArray>) {
          ^
Main.kt:235:11: 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:242:11: 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:259:11: 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 = 1_000_000_007
/**
 * (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 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
}
class Solver(stream: InputStream, private val out: java.io.PrintWriter) {
  private val reader = BufferedReader(InputStreamReader(stream), 32768)

  private val N = ni()
  fun solve() {
    val th = Thread(null, Runnable {
      _solve()
    },"solve", 1 shl 26)
    th.start()
    th.join()
  }
  
  fun _solve() {
    out.println(if (solve2()) "Yes" else "No")
  }
  
  fun solve2(): Boolean {
    val (from, to) = na2(N - 1, -1)
    val g = packUGraph(N, from, to)
    
    val leaf = g.count { it.size == 1 }
    if (leaf == 2) return true
    
    val s = g.indexOfFirst { it.size == 1 }
    
    val path = mutableListOf<Int>()
    fun dfs(v: Int, par: Int): Boolean {
      path += v
      if (v != s && g[v].size == 1) return true

      for (u in g[v]) {
        if (u == par) continue
        if (dfs(u, v)) return true
      }

      return false
    }


    dfs(s, -1)

    debug{"$path"}
//    if (path.size%2 == 0) return false
    val rt = path[path.size/2]
    debug{"rt:$rt"}
    val (dist, _, _) = traceBfs(g, rt)

    var ok = true
    for (v in 0 until N) {
      if (g[v].size == 1) {
        ok = ok && dist[v] == dist[s]
      }
      else if (v != rt) {
        ok = ok && g[v].size == 2
      }
    }
    return ok
  }













































  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()}
}

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