#231383 (Java21) No.121 傾向と対策：門松列（その２）

• 問題: No.121 傾向と対策：門松列（その２）
• ユーザー: yuya178
• 提出日時: 2018-01-22 20:00:35
• 言語: Java21 (openjdk 21)
• 結果: AC
• 実行時間: 3,402 ms / 5,000 ms
• コード長: 5,738 bytes
• コンパイル時間: 2,660 ms
• コンパイル使用メモリ: 84,176 KB
• 実行使用メモリ: 223,060 KB
• 最終ジャッジ日時: 2024-06-28 18:44:28
• 合計ジャッジ時間: 10,300 ms
• ジャッジサーバーID （参考情報）: judge2 / judge5

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	195 ms; 48,432 KB
testcase_01	AC	253 ms; 52,328 KB
testcase_02	AC	84 ms; 39,232 KB
testcase_03	AC	482 ms; 131,532 KB
testcase_04	AC	3,402 ms; 223,060 KB
testcase_05	AC	572 ms; 131,820 KB
testcase_06	AC	517 ms; 130,680 KB
testcase_07	AC	637 ms; 130,556 KB
testcase_08	AC	719 ms; 132,660 KB

ソースコード

import java.io.*;
import java.util.*;
import java.math.*;
// import java.awt.Point;
 
public class Main {
    InputStream is;
    PrintWriter out;
    String INPUT = "";
 
    long MOD = 1_000_000_007;
    long inf = Long.MAX_VALUE;

    void solve(){
        int n = ni();
        int[] a = new int[n];
        int[] b = new int[n];
        for(int i = 0; i < n; i++){
            a[i] = ni();
            b[i] = a[i];
        }
        Arrays.sort(b);
        Map<Integer,Integer> map = new HashMap<>();
        for(int i = 0; i < n; i++){
            if(map.containsKey(b[i])) continue;
            map.put(b[i], map.size());
        }
        BIT bi = new BIT(n);
        long[] lu = new long[n];
        long[] ld = new long[n];
        long[] ru = new long[n];
        long[] rd = new long[n];
        for(int i = 0; i < n; i++){
            int id = map.get(a[i]);
            ld[i] = bi.sum(0,id);
            lu[i] = bi.sum(id+1,n);
            bi.accumlate(id,1);
        }
        BIT bi2 = new BIT(n);
        for(int i = n-1; i >= 0; i--){
            int id = map.get(a[i]);
            rd[i] = bi2.sum(0,id);
            ru[i] = bi2.sum(id+1,n);
            bi2.accumlate(id, 1);
        }
        long ans = 0;
        for(int i = 0; i < n; i++){
            ans += ld[i]*rd[i] + lu[i]*ru[i];
        }
        long[] R = new long[n];
        long[] L = new long[n];
        for(int i = 0; i < n; i++){
            int id = map.get(a[i]);
            R[id]++;
        }
        long res = 0;
        for(int i = 0; i < n; i++){
            int id = map.get(a[i]);
            res -= L[id]*R[id];
            ans -= res;
            R[id]--;
            L[id]++;
            res += L[id]*R[id];
        }
        out.println(ans);
    }

    class BIT {
    private int n;
    private long[] bit;
    public BIT(int n) {
        this.n = n;
        bit = new long[n+1];
    }

    public void accumlate(int index,long num) {
        index++;
        while(index<=n) {
            bit[index] += num;
            index+=index&-index;
        }
    }

    /* [begin , end) */
    public long sum(int begin,int end) {
        return sum(end) - sum(begin);
    }

    private long sum(int i) {
        long s = 0;
        while(i>0) {
            s+=bit[i];
            i-=i&-i;
        }
        return s;
    }

    public long get(int index) {
        return sum(index,index+1);
    }

    public void set(int index,long num) {
        accumlate(index,num-(sum(index)-sum(index-1)));
    }

    public String toString() {
        long[] value = new long[n];
        for(int i=0;i<n;i++) {
            value[i] = get(i);
        }
        return Arrays.toString(value);
    }
}

    void run() throws Exception
    {
        is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
        out = new PrintWriter(System.out);
        long s = System.currentTimeMillis();
        solve();
        out.flush();
        if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
    }
    
    public static void main(String[] args) throws Exception { new Main().run(); }
    
    private byte[] inbuf = new byte[1024];
    private int lenbuf = 0, ptrbuf = 0;
    
    private int readByte()
    {
        if(lenbuf == -1)throw new InputMismatchException();
        if(ptrbuf >= lenbuf){
            ptrbuf = 0;
            try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
            if(lenbuf <= 0)return -1;
        }
        return inbuf[ptrbuf++];
    }
    
    private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
    private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
    
    private double nd() { return Double.parseDouble(ns()); }
    private char nc() { return (char)skip(); }
    
    private String ns()
    {
        int b = skip();
        StringBuilder sb = new StringBuilder();
        while(!(isSpaceChar(b) && b != ' ')){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    
    private char[] ns(int n)
    {
        char[] buf = new char[n];
        int b = skip(), p = 0;
        while(p < n && !(isSpaceChar(b))){
            buf[p++] = (char)b;
            b = readByte();
        }
        return n == p ? buf : Arrays.copyOf(buf, p);
    }
    
    private char[][] nm(int n, int m)
    {
        char[][] map = new char[n][];
        for(int i = 0;i < n;i++)map[i] = ns(m);
        return map;
    }
    
    private int[] na(int n)
    {
        int[] a = new int[n];
        for(int i = 0;i < n;i++)a[i] = ni();
        return a;
    }
    
    private int ni()
    {
        int num = 0, b;
        boolean minus = false;
        while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        
        while(true){
            if(b >= '0' && b <= '9'){
                num = num * 10 + (b - '0');
            }else{
                return minus ? -num : num;
            }
            b = readByte();
        }
    }
    
    private long nl()
    {
        long num = 0;
        int b;
        boolean minus = false;
        while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        
        while(true){
            if(b >= '0' && b <= '9'){
                num = num * 10 + (b - '0');
            }else{
                return minus ? -num : num;
            }
            b = readByte();
        }
    }
    
    private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
 
}