結果

問題 No.1300 Sum of Inversions
ユーザー tenten
提出日時 2023-02-02 09:11:58
言語 Java
(openjdk 23)
結果
AC  
実行時間 1,153 ms / 2,000 ms
コード長 3,519 bytes
コンパイル時間 2,761 ms
コンパイル使用メモリ 84,036 KB
実行使用メモリ 72,748 KB
最終ジャッジ日時 2024-07-01 23:54:24
合計ジャッジ時間 35,172 ms
ジャッジサーバーID
（参考情報） 		judge5 / 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 * 3
other AC * 34
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.stream.*;

public class Main {
    static final int MOD = 998244353;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int[] values = new int[n];
        TreeMap<Integer, Integer> compress = new TreeMap<>();
        for (int i = 0; i < n; i++) {
            values[i] = -sc.nextInt();
            compress.put(values[i], null);
        }
        int size = 1;
        for (int x : compress.keySet()) {
            compress.put(x, size++);
        }
        BinaryIndexedTree firstValue = new BinaryIndexedTree(size);
        BinaryIndexedTree firstCount = new BinaryIndexedTree(size);
        BinaryIndexedTree secondValue = new BinaryIndexedTree(size);
        BinaryIndexedTree secondCount = new BinaryIndexedTree(size);
        long ans = 0;
        for (int x : values) {
            int idx = compress.get(x);
            int y = -x;
            ans += secondValue.getSum(idx - 1) + y * secondCount.getSum(idx - 1) % MOD;
            ans %= MOD;
            secondCount.add(idx, firstCount.getSum(idx - 1));
            secondValue.add(idx, (firstValue.getSum(idx - 1) + y * firstCount.getSum(idx - 1) % MOD) % MOD);
            firstCount.add(idx, 1);
            firstValue.add(idx, y);
        }
        System.out.println(ans);
    }
}

class BinaryIndexedTree {
    static final int MOD = 998244353;
    int size;
    long[] tree;
    
    public BinaryIndexedTree(int size) {
        this.size = size;
        tree = new long[size];
    }
    
    public void add(int idx, long value) {
        int mask = 1;
        while (idx < size) {
            if ((idx & mask) != 0) {
                tree[idx] += value;
                tree[idx] %= MOD;
                idx += mask;
            }
            mask <<= 1;
        }
    }
    
    public long getSum(int from, int to) {
        return (getSum(to) - getSum(from - 1) + MOD) % MOD;
    }
    
    public long getSum(int x) {
        int mask = 1;
        long ans = 0;
        while (x > 0) {
            if ((x & mask) != 0) {
                ans += tree[x];
                ans %= MOD;
                x -= mask;
            }
            mask <<= 1;
        }
        return ans;
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}
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