結果

問題 No.1507 Road Blocked
コンテスト
ユーザー shojin_pro
提出日時 2021-05-14 23:20:45
言語 Java
(openjdk 23)
結果
WA  
実行時間 -
コード長 4,738 bytes
コンパイル時間 2,342 ms
コンパイル使用メモリ 86,996 KB
実行使用メモリ 102,112 KB
最終ジャッジ日時 2024-10-02 05:02:14
合計ジャッジ時間 20,580 ms
ジャッジサーバーID
（参考情報） 		judge1 / 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 * 1 WA * 29
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 FastScanner sc = new FastScanner(System.in);
    static PrintWriter pw = new PrintWriter(System.out);
    static StringBuilder sb = new StringBuilder();
    static long mod = (long) 998244353;
    
    static int N;
    static int[] A = new int[1 << 18], B = new int[1 << 18];
    static long[] dp = new long[1 << 18];
    static ArrayList<ArrayList<Integer>> G = new ArrayList<>();
    
    static void dfs(int pos, int pre) {
    	dp[pos] = 1;
    	for (int i : G.get(pos)) {
    		if (i == pre) continue;
    		dfs(i, pos);
    		dp[pos] += dp[i];
    	}
    }

    public static void main(String[] args) throws Exception {
        solve();
        pw.flush();
    }

    public static void solve() {
    	N = sc.nextInt();
    	for(int i = 0; i < (1<<18); i++) G.add(new ArrayList<>());
    	for (int i = 1; i <= N - 1; i++) {
    		A[i] = sc.nextInt(); B[i] = sc.nextInt();
    		G.get(A[i]).add(B[i]);
    		G.get(B[i]).add(A[i]);
    	}
    
    	dfs(1, -1);
    
    	long Answer = 0;
    	for (int i = 1; i <= N - 1; i++) {
    		long r = Math.min(dp[A[i]], dp[B[i]]);
    		Answer += r * (long)(N - r);
    	}
    	long deno = 1L*(long)N*(long)(N-1)/2L*(long)(N-1);
    	Answer = (deno-Answer);
    	long gcd = gcd(Answer,deno);
    	Answer /= gcd; deno /= gcd;
    	Answer %= mod;
    	long ans = rep2(deno,mod-2,mod);
    	Answer *= ans;
    	Answer %= mod;
    	pw.println(Answer);
    }
    
    private static long gcd(long a, long b)
    {
        while (b > 0)
        {
            long temp = b;
            b = a % b; // % is remainder
            a = temp;
        }
        return a;
    }
    
    private static long rep2(long b, long n, long mod){
        if(n == 0) return 1;
        long bn = rep2(b,n/2,mod);
        if(n % 2 == 0){
            return (bn*bn)%mod;
        }else{
            return (bn*bn)%mod*b%mod;
        }
    }

    static class GeekInteger {
        public static void save_sort(int[] array) {
            shuffle(array);
            Arrays.sort(array);
        }

        public static int[] shuffle(int[] array) {
            int n = array.length;
            Random random = new Random();
            for (int i = 0, j; i < n; i++) {
                j = i + random.nextInt(n - i);
                int randomElement = array[j];
                array[j] = array[i];
                array[i] = randomElement;
            }
            return array;
        }

        public static void save_sort(long[] array) {
            shuffle(array);
            Arrays.sort(array);
        }

        public static long[] shuffle(long[] array) {
            int n = array.length;
            Random random = new Random();
            for (int i = 0, j; i < n; i++) {
                j = i + random.nextInt(n - i);
                long randomElement = array[j];
                array[j] = array[i];
                array[i] = randomElement;
            }
            return array;
        }

    }
}

class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;

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

    public FastScanner(FileReader in) {
        reader = new BufferedReader(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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