#882103 (Java21) No.2351 Butterfly in Summer

• 問題: No.2351 Butterfly in Summer
• ユーザー: Asahi
• 提出日時: 2023-06-16 22:58:57
• 言語: Java21 (openjdk 21)
• 結果: AC
• 実行時間: 84 ms / 2,000 ms
• コード長: 6,913 bytes
• コンパイル時間: 2,563 ms
• コンパイル使用メモリ: 84,336 KB
• 実行使用メモリ: 57,460 KB
• 最終ジャッジ日時: 2024-06-24 15:58:54
• 合計ジャッジ時間: 5,438 ms
• ジャッジサーバーID （参考情報）: judge4 / judge2

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	82 ms; 57,116 KB
testcase_01	AC	82 ms; 57,156 KB
testcase_02	AC	84 ms; 57,024 KB
testcase_03	AC	82 ms; 57,200 KB
testcase_04	AC	84 ms; 57,176 KB
testcase_05	AC	84 ms; 57,020 KB
testcase_06	AC	83 ms; 57,336 KB
testcase_07	AC	83 ms; 57,112 KB
testcase_08	AC	82 ms; 57,120 KB
testcase_09	AC	83 ms; 57,344 KB
testcase_10	AC	83 ms; 57,460 KB
testcase_11	AC	84 ms; 57,024 KB
testcase_12	AC	82 ms; 57,300 KB
testcase_13	AC	83 ms; 57,196 KB
testcase_14	AC	82 ms; 57,308 KB
testcase_15	AC	83 ms; 57,064 KB
testcase_16	AC	83 ms; 57,096 KB
testcase_17	AC	82 ms; 57,048 KB
testcase_18	AC	83 ms; 57,136 KB
testcase_19	AC	83 ms; 57,132 KB
testcase_20	AC	82 ms; 57,388 KB
testcase_21	AC	84 ms; 57,196 KB
testcase_22	AC	84 ms; 57,432 KB
testcase_23	AC	83 ms; 57,388 KB

ソースコード

import java.util.*;
import java.io.*;

class Main{

    void solve(PrintWriter out, In in) { 
        int n = in.nextInt() , k = in.nextInt();      
        long MOD = 998244353;
        Combination cm = new Combination(1000000,MOD);
        // kC2 * 2 * N!/(N-1)!
        long kC2 = cm.nck(k,2) % MOD;
        long combi = cm.facts[n] * cm.inv(cm.facts[n-1]) % MOD;
        long high = kC2 * 2 * combi % MOD;
        long low = cm.modpow(k,n) % MOD;
        out.print(high * cm.inv(low) % MOD);
    }   
    class Combination {
        int n;
        long mod;
        long[] facts;
        Combination(int n, long mod) {
            this.n = n;
            this.mod = mod;
            facts = new long[n];
            facts[0] = 1;
            for (int i = 1; i < n; i++) {
                facts[i] = facts[i - 1] * i % mod;
            }
        }
        long modpow(long a, long b) {
            if (b == 0) return 1;
            else if (b == 1) return a;

            long x = modpow(a, b / 2);
            return b % 2 == 0 ? x * x % mod : x * (x * a % mod) % mod;
        }
        long inv(long n) {
            return modpow(n, mod - 2);
        }
        long nck(int n, int k) {
            return facts[n] * (inv(facts[n - k]) * inv(facts[k]) % mod) % mod;
        }
    }
    public static void main(String[] args) {
        PrintWriter out = new PrintWriter(System.out);
        In in  = new In();
        new Main().solve(out,in);
        out.flush();
    }
}
class Pair implements Comparable<Pair>{
    private int first ;
    private int second;
    Pair(int first,int second) {
        this.first = first;
        this.second = second;
    }
    int first()  { 
        return this.first ;
    }
    int second() { 
        return this.second;
    }
    @Override
    public boolean equals(Object o) {
        if (!(o instanceof Pair)) {
            return false;
        }
        Pair that = (Pair)o;
        return first == that.first && second == that.second;
    }
    @Override
    public int hashCode() {
        return Objects.hash(first, second);
    }
    @Override
    public int compareTo(Pair o) {
        return first == o.first ? Integer.compare(second, o.second) : Integer.compare(first, o.first);
    }
    @Override
    public String toString(){ 
        return first()+" "+second();
    }
}
class PairII {
    private int first;
    private int second;
    private int third;
    PairII(int first, int second, int third) {
        this.first = first;
        this.second = second;
        this.third = third;
    }
    int first() {
        return this.first;
    }
    int second() {
        return this.second;
    }
    int third() {
        return this.third;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }

        PairII other = (PairII) obj;
        return this.first == other.first && this.second == other.second && this.third == other.third;
    }

    @Override
    public int hashCode() {
        int result = 17;
        result = 31 * result + first;
        result = 31 * result + second;
        result = 31 * result + third;
        return result;
    }
    @Override 
    public String toString() {
        return this.first+" "+this.second+" "+this.third;
    }
}
class In{
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { 
        if (hasNextByte()) return buffer[ptr++]; else return -1;
    }
    private static boolean isPrintableChar(int c) { 
        return 33 <= c && c <= 126;
    }
    public boolean hasNext() { 
        while(hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++; 
        }
        return hasNextByte();
    }
    String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    double nextDouble() { 
        return Double.parseDouble(next());
    }
    int [] IntArray(int n) {
        final int [] Array = new int [n];
        for(int i = 0 ; i < n ; i ++ ) {
            Array[i] = nextInt();
        }
        return Array;
    }
    int [][] IntArray(int n , int m) {
        final int [][] Array = new int [n][m];
        for(int i = 0 ; i < n ; i ++ ) {
            Array[i] = IntArray(m);
        }
        return Array;
    }   
    long [] LongArray(int n) {
        final long [] Array = new long [n];
        for(int i = 0 ; i < n ; i ++ ) {
            Array[i] = nextLong();
        }
        return Array;
    }
    long [][] LongArray(int n , int m) {
        final long [][] Array = new long [n][m];
        for(int i = 0 ; i < n ; i ++ ) {
            Array[i] = LongArray(m);
        }
        return Array;
    }
    String [] StringArray(int n) {
        final String [] Array = new String [n];
        for(int i = 0 ; i < n ; i ++ ) {
            Array[i] = next();
        }
        return Array;
    }
    char [] CharArray(int n) {
        final char [] Array = new char[n];
        for(int i = 0 ; i < n ; i ++ ) {
            Array[i] = next().charAt(0);
        }
        return Array;
    }
    char [][] CharArray(int n , int m) {
        final char [][] Array = new char [n][m];
        for(int i = 0 ; i < n ; i ++ ) {
            Array[i] = next().toCharArray();
        }
        return Array;
    }
}