結果

問題 No.797 Noelちゃんとピラミッド
コンテスト
ユーザー watarimaycry2
提出日時 2020-10-07 14:29:31
言語 Java
(openjdk 23)
結果
AC  
実行時間 347 ms / 2,000 ms
コード長 4,335 bytes
記録
記録タグの例:
初AC ショートコード 純ショートコード 純主流ショートコード 最速実行時間
コンパイル時間 2,494 ms
コンパイル使用メモリ 80,384 KB
実行使用メモリ 62,804 KB
最終ジャッジ日時 2024-07-20 03:25:33
合計ジャッジ時間 18,599 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 * 3
other AC * 60
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 #
raw source code 

import java.util.*; import java.io.*; import java.math.*;
public class Main{
	static void solve(){//Here is the main function
      int N = nextInt();
      ArrayList<Integer> list = nextIntArray();
      int mod = 1000000007;
      Combination comb = new Combination(N, mod);
      long output = 0;
      for(int i = 0; i < N; i++){
        output += list.get(i) * comb.nCk(N - 1, i);
        output %= mod;
      }
      myout(output);
	}
	//Method addition frame start

static class Combination{
        long[] kaijo;
        long[] inverse;
        long mod;
        Combination(int N, long mod){
                  this.mod = mod;
                kaijo = new long[N + 1];
                inverse = new long[N + 1];
                kaijo[0] = 1;
                inverse[0] = 1;
                for(int i = 1; i <= N; i++){
                        kaijo[i] = kaijo[i - 1] * (long)i % mod;
                        inverse[i] = inverse[i - 1] * this.pow((long)i, mod - 2) % mod;
                }
        }
        private long pow(long x, long n) {
                long ans = 1;
                while (n > 0) {
                        if ((n & 1) == 1){
                          ans = ans * x;
                          if(mod != -1){ans %= mod;}
                        }
                        x = x * x;
                        if(mod != -1){x %= mod;}
                        n >>= 1;
                }
                return ans;
        }
        public long nCk(int n, int k){
                if(k < 0 || k > n){
                        return 0;
                }
                return ((kaijo[n] * inverse[k]) % mod * inverse[n - k]) % mod;
        }
}

	//Method addition frame end

	//Don't have to see. start------------------------------------------
	static class InputIterator{
		ArrayList<String> inputLine = new ArrayList<>(1024);
		int index = 0; int max; String read;
		InputIterator(){
			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
			try{
				while((read = br.readLine()) != null){
					inputLine.add(read);
				}
			}catch(IOException e){}
			max = inputLine.size();
		}
		boolean hasNext(){return (index < max);}
		String next(){
			if(hasNext()){
				return inputLine.get(index++);
			}else{
				throw new IndexOutOfBoundsException("There is no more input");
			}
		}
	}
	static HashMap<Integer, String> CONVSTR = new HashMap<>();
	static InputIterator ii = new InputIterator();//This class cannot be used in reactive problem.
	static PrintWriter out = new PrintWriter(System.out);
	static void flush(){out.flush();}
	static void myout(Object t){out.println(t);}
	static void myerr(Object t){System.err.print("debug:");System.err.println(t);}
	static String next(){return ii.next();}
	static boolean hasNext(){return ii.hasNext();}
	static int nextInt(){return Integer.parseInt(next());}
	static long nextLong(){return Long.parseLong(next());}
	static double nextDouble(){return Double.parseDouble(next());}
	static ArrayList<String> nextStrArray(){return myconv(next(), 8);}
	static ArrayList<String> nextCharArray(){return myconv(next(), 0);}
	static ArrayList<Integer> nextIntArray(){
		ArrayList<String> input = nextStrArray(); ArrayList<Integer> ret = new ArrayList<>(input.size());
		for(int i = 0; i < input.size(); i++){
			ret.add(Integer.parseInt(input.get(i)));
		}
		return ret;
	}
	static ArrayList<Long> nextLongArray(){
		ArrayList<String> input = nextStrArray(); ArrayList<Long> ret = new ArrayList<>(input.size());
		for(int i = 0; i < input.size(); i++){
			ret.add(Long.parseLong(input.get(i)));
		}
		return ret;
	}
	@SuppressWarnings("unchecked")
	static String myconv(Object list, int no){//only join
		String joinString = CONVSTR.get(no);
		if(list instanceof String[]){
			return String.join(joinString, (String[])list);
		}else if(list instanceof ArrayList){
			return String.join(joinString, (ArrayList)list);
		}else{
			throw new ClassCastException("Don't join");
		}
	}
	static ArrayList<String> myconv(String str, int no){//only split
		String splitString = CONVSTR.get(no);
		return new ArrayList<String>(Arrays.asList(str.split(splitString)));
	}
	public static void main(String[] args){
		CONVSTR.put(8, " "); CONVSTR.put(9, "\n"); CONVSTR.put(0, "");
		solve();flush();
	}
	//Don't have to see. end------------------------------------------
}
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