結果

問題 No.1103 Directed Length Sum
コンテスト
ユーザー shojin_pro
提出日時 2020-07-04 00:09:57
言語 Java
(openjdk 23)
結果
AC  
実行時間 956 ms / 3,000 ms
コード長 3,091 bytes
コンパイル時間 2,393 ms
コンパイル使用メモリ 78,792 KB
実行使用メモリ 81,360 KB
最終ジャッジ日時 2024-09-17 05:13:30
合計ジャッジ時間 17,062 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge2
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 * 2
other AC * 22
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 # 

import java.util.*;
import java.io.*;
 
public class Main {
    static boolean[] arrived;
    static long[] cum;
    public static void main(String[] args) throws Exception {
        long mod = (long)Math.pow(10,9)+7;
        FastScanner sc = new FastScanner(System.in);
        int n = sc.nextInt();
        int[] from = new int[n+1];
        cum = new long[n+1];
        for(int i = 1; i <= n; i++){
            cum[i] += cum[i-1]+i;
        }
        for(int i = 0; i < n-1; i++){
            int a = sc.nextInt();
            int b = sc.nextInt();
            from[b] = a;
        }
        long ans = 0;
        int[] step = new int[n+1];
        boolean[] arrived = new boolean[n+1];
        Deque<Integer> q = new ArrayDeque<>();
        for(int i = 1; i <= n; i++){
            int cnt = 0;
            if(arrived[i]){
                continue;
            }
            int now = i;
            while(from[now] != 0){
                if(arrived[now]){
                    cnt = step[now];
                    break;
                }else{
                    arrived[now] = true;
                    q.add(now);
                }
                now = from[now];
            }
            while(q.size() != 0){
                long tmp = cum[q.size()+cnt];
                ans += tmp;
                ans %= mod;
                int prev = q.pollFirst();
                step[prev] = q.size()+1+cnt;
            }
        }
        System.out.println(ans);
    }
}

class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;
    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    }

    public long nextLong() {
        return Long.parseLong(next());
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

    public double nextDouble() {
         return Double.parseDouble(next());
    }
    
    public String[] nextArray(int n) {
        String[] a = new String[n];
        for (int i = 0; i < n; i++)
            a[i] = next();
        return a;
    }

    public int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = nextInt();
        return a;
    }

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } 
}
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