結果

問題 No.3091 The Little Match Boy
コンテスト
ユーザー tenten
提出日時 2025-04-07 15:48:04
言語 Java
(openjdk 23)
結果
AC  
実行時間 179 ms / 2,000 ms
コード長 3,609 bytes
コンパイル時間 3,433 ms
コンパイル使用メモリ 82,216 KB
実行使用メモリ 59,628 KB
最終ジャッジ日時 2025-04-07 15:48:20
合計ジャッジ時間 14,204 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge1
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ファイルパターン 結果
other AC * 62
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.io.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        int[] place = IntStream.range(0, n).toArray();
        Set<Pair> ans = new HashSet<>();
        while (m-- > 0) {
            int x = sc.nextInt();
            ans.add(new Pair(place[x - 1], place[x]));
            int tmp = place[x - 1];
            place[x - 1] = place[x];
            place[x] = tmp;
        }
        System.out.println(ans.size());
    }
    
    static class Pair {
        int a;
        int b;
        
        public Pair(int x, int y) {
            a = Math.min(x, y);
            b = Math.max(x, y);
        }
        
        public int hashCode() {
            return Objects.hash(a, b);
        }
        
        public boolean equals(Object o) {
            Pair p = (Pair)o;
            return a == p.a && b == p.b;
        }
    }
}

class FastScanner {
    private DataInputStream din;
    private byte[] buffer;
    private int bufferPointer, bytesRead;
    private static final int BUFFER_SIZE = 1 << 16; // 65,536 バイト

    public FastScanner() {
        din = new DataInputStream(System.in);
        buffer = new byte[BUFFER_SIZE];
        bufferPointer = bytesRead = 0;
    }

    private byte read() {
        try {
            if (bufferPointer == bytesRead) {
                bytesRead = din.read(buffer, 0, BUFFER_SIZE);
                if (bytesRead == -1) return -1;
                bufferPointer = 0;
            }
            return buffer[bufferPointer++];
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public String next() {
        byte b = read();
        // 空白文字を読み飛ばす
        while (isSpaceChar(b)) {
            b = read();
        }
        StringBuilder sb = new StringBuilder();
        while (!isSpaceChar(b)) {
            sb.append((char) b);
            b = read();
        }
        return sb.toString();
    }

    public int nextInt() {
        int ret = 0;
        byte c = read();
        while (isSpaceChar(c)) c = read();
        boolean neg = (c == '-');
        if (neg) c = read();
        do {
            ret = ret * 10 + c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return neg ? -ret : ret;
    }

    public long nextLong() {
        long ret = 0;
        byte c = read();
        while (isSpaceChar(c)) c = read();
        boolean neg = (c == '-');
        if (neg) c = read();
        do {
            ret = ret * 10L + c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return neg ? -ret : ret;
    }

    public double nextDouble() {
        double ret = 0, div = 1;
        byte c = read();
        while (isSpaceChar(c)) c = read();
        boolean neg = (c == '-');
        if (neg) c = read();
        do {
            ret = ret * 10 + c - '0';
            c = read();
        } while (!isSpaceChar(c) && c != '.');
        if (c == '.') {
            while (!isSpaceChar(c = read())) {
                ret += (c - '0') / (div *= 10);
            }
        }
        return neg ? -ret : ret;
    }

    private boolean isSpaceChar(byte c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public void close() {
        try {
            if (din != null) din.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}
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