結果

問題 No.2235 Line Up Colored Balls
ユーザー kakel-san
提出日時 2023-07-26 21:26:26
言語 C#(csc)
(csc 3.9.0)
結果
AC  
実行時間 71 ms / 2,000 ms
コード長 3,273 bytes
コンパイル時間 1,085 ms
コンパイル使用メモリ 114,588 KB
実行使用メモリ 26,496 KB
最終ジャッジ日時 2024-10-03 07:51:51
合計ジャッジ時間 6,514 ms
ジャッジサーバーID
(参考情報)
judge4 / judge1
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 * 4
other AC * 55
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
Microsoft (R) Visual C# Compiler version 3.9.0-6.21124.20 (db94f4cc)
Copyright (C) Microsoft Corporation. All rights reserved.

ソースコード

diff #
プレゼンテーションモードにする

using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
static int NN => int.Parse(ReadLine());
static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
public static void Main()
{
Solve();
}
static void Solve()
{
var n = NN;
var a = NList;
var sum = a.Sum();
var mod = 1_000_000_007;
var revsum = Exp(sum, mod - 2, mod);
var ans = (long)sum;
foreach (var ai in a)
{
ans = (ans + mod - (long)ai * (ai - 1) % mod * revsum % mod) % mod;
}
WriteLine(ans);
}
static long Exp(int n, int k, int mod)
{
if (k == 0) return 1;
if (k == 1) return n % mod;
var half = Exp(n, k / 2, mod);
var result = (half * half) % mod;
return ((k % 2) == 0) ? result : ((result * n) % mod);
}
static List<int[]> NCRList(int n, int r)
{
var res = new List<int[]>();
_NCRList(n, r, new List<int>(), res);
return res;
}
static void _NCRList(int n, int r, List<int> list, List<int[]> res)
{
if (list.Count == r) res.Add(list.ToArray());
for (var i = list.Count == 0 ? 0 : (list.Last() + 1); i < n; ++i)
{
list.Add(i);
_NCRList(n, r, list, res);
list.RemoveAt(list.Count - 1);
}
}
class NCR
{
int[] facts;
int[] revFacts;
int mod;
public NCR(int n, int mod)
{
facts = new int[n + 1];
revFacts = new int[n + 1];
this.mod = mod;
facts[0] = 1;
var tmp = 1L;
for (var i = 1; i <= n; ++i)
{
tmp = (tmp * i) % mod;
facts[i] = (int)tmp;
}
tmp = Exp(facts[n], mod - 2);
revFacts[n] = (int)tmp;
for (var i = n; i > 1; --i)
{
tmp = (tmp * i) % mod;
revFacts[i - 1] = (int)tmp;
}
revFacts[0] = 1;
}
public long Exp(long n, long k)
{
n = n % mod;
if (k == 0) return 1;
if (k == 1) return n;
var half = Exp(n, k / 2);
var result = (half * half) % mod;
return ((k % 2) == 0) ? result : ((result * n) % mod);
}
public long Calc(int n, int r)
{
return (long)facts[n] * revFacts[r] % mod * revFacts[n - r] % mod;
}
/// <summary>nr</summary>
public long Calc2(int n, int r)
{
var tmp = 1L;
for (var i = 0; i < r; ++i)
{
tmp = tmp * (n - i) % mod;
}
return tmp * revFacts[r] % mod;
}
public long NPR(int n, int r)
{
return (long)facts[n] * revFacts[r] % mod;
}
public long Fact(int n)
{
return facts[n];
}
public long RevFact(int n)
{
return revFacts[n];
}
}
}
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