結果

問題 No.1507 Road Blocked
コンテスト
ユーザー dot_haraai
提出日時 2021-06-19 17:18:48
言語 Nim
(2.2.0)
結果
AC  
実行時間 72 ms / 2,000 ms
コード長 1,660 bytes
コンパイル時間 3,851 ms
コンパイル使用メモリ 86,528 KB
実行使用メモリ 16,384 KB
最終ジャッジ日時 2024-06-22 22:11:05
合計ジャッジ時間 7,530 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge4
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 * 3
other AC * 30
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
/home/judge/data/code/Main.nim(2, 18) Warning: Use the new 'sugar' module instead; future is deprecated [Deprecated]
/home/judge/data/code/Main.nim(1, 8) Warning: imported and not used: 'times' [UnusedImport]
/home/judge/data/code/Main.nim(2, 26) Warning: imported and not used: 'strformat' [UnusedImport]
/home/judge/data/code/Main.nim(2, 18) Warning: imported and not used: 'future' [UnusedImport]
/home/judge/data/code/Main.nim(2, 37) Warning: imported and not used: 'deques' [UnusedImport]
/home/judge/data/code/Main.nim(1, 41) Warning: imported and not used: 'algorithm' [UnusedImport]
/home/judge/data/code/Main.nim(1, 52) Warning: imported and not used: 'tables' [UnusedImport]
/home/judge/data/code/Main.nim(1, 60) Warning: imported and not used: 'sets' [UnusedImport]
/home/judge/data/code/Main.nim(1, 66) Warning: imported and not used: 'lists' [UnusedImport]
/home/judge/data/code/Main.nim(1, 73) Warning: imported and not used: 'intsets' [UnusedImport]
/home/judge/data/code/Main.nim(2, 8) Warning: imported and not used: 'critbits' [UnusedImport]

ソースコード

diff # 

import times, strutils, sequtils, math, algorithm, tables, sets, lists, intsets
import critbits, future, strformat, deques
template `max=`(x,y) = x = max(x,y)
template `min=`(x,y) = x = min(x,y)
template `mod=`(x,y) = x = x mod y
template scan2 = (scan(), scan())
template scan3 = (scan(), scan())
let read* = iterator: string {.closure.} =
    while true: (for s in stdin.readLine.split: yield s)
proc scan(): int = read().parseInt
proc scanf(): float = read().parseFloat
proc toInt(c:char): int =
    return int(c) - int('0')




# 拡張ユークリッド互除法

proc xgcd(a,b:int):(int,int,int)=
  var
    b = b
    x0=1
    y0=0
    x1=0
    y1=1
    q:int
    a = a
  while b!=0:
    (q,a,b) = (a.div(b),b,a.mod(b))
    (x0,x1)=(x1,x0-q*x1)
    (y0,y1)=(y1,y0-q*y1)
  return (a,x0,y0)

# modの逆元
proc modinv(a,m:int):int=
  var (g,x,y)=xgcd(a,m)
  if g!=1:
    return -1
  else:
    return ((x mod m)+m).mod(m)


const md = 998244353
proc solve()=
  var
    n =scan()
    es = newseqwith(n,newseq[int]())
    children = newseqwith(n,0)
  for i in 0..<n-1:
    var
      u = scan()-1
      v = scan()-1
    es[u].add(v)
    es[v].add(u)
  
  proc dfs(p,par:int):int=
    result=1
    for nxt in es[p]:
      if nxt == par:continue
      else:
        result+=dfs(nxt,p)
    children[p]=result
    return result

  discard dfs(0,-1)
  var
    pattern = 0
    d = ((n*(n-1)).div(2).mod(md)*(n-1)).mod(md).modinv(md)
  #echo children
  for p in 1..<n:
    pattern+=((n-children[p])*(n-children[p]-1)).div(2)+(children[p]*(children[p]-1)).div(2)
    pattern.mod=md
  #echo pattern
  
  echo ((pattern * d).mod(md)+md).mod(md)
  #echo d


  
  
solve()
0