結果

問題 No.1115 二つの数列 / Two Sequences
ユーザー uwi
提出日時 2020-07-17 21:25:39
言語 Java
(openjdk 23)
結果
AC  
実行時間 136 ms / 2,000 ms
コード長 4,341 bytes
コンパイル時間 4,222 ms
コンパイル使用メモリ 85,124 KB
実行使用メモリ 54,148 KB
最終ジャッジ日時 2024-11-29 21:07:13
合計ジャッジ時間 9,346 ms
ジャッジサーバーID
（参考情報） 		judge1 / 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 * 5
other AC * 35
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 #
プレゼンテーションモードにする

package contest200717;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
public class C {
    InputStream is;
    PrintWriter out;
    String INPUT = "";
    
    void solve()
    {
        int n = ni();
        int[] a = na(n);
        int[] b = na(n);
        int[] ia = new int[n];
        for(int i = 0;i < n;i++){
            a[i]--;
            ia[a[i]] = i;
        }
        
        int[] f = new int[n];
        for(int i = 0;i < n;i++){
            f[ia[b[i]-1]] = i;
        }
        out.println(inversion(f));
    }
    
    public static long inversion(int[] a)
    {
        int n = a.length;
        int[] b = a;
        int[] ft = new int[n+1];
        long inv = 0;
        for(int i = n-1;i >= 0;i--){
            inv += sumFenwick(ft, b[i]-1);
            addFenwick(ft, b[i], 1);
        }
        return inv;
    }
    
    public static int sumFenwick(int[] ft, int i)
    {
        int sum = 0;
        for(i++;i > 0;i -= i&-i)sum += ft[i];
        return sum;
    }
    
    public static void addFenwick(int[] ft, int l, int r, int v)
    {
        addFenwick(ft, l, v);
        addFenwick(ft, r, -v);
    }
    
    public static void addFenwick(int[] ft, int i, int v)
    {
        if(v == 0 || i < 0)return;
        int n = ft.length;
        for(i++;i < n;i += i&-i)ft[i] += v;
    }
    
    public static int firstGEFenwick(int[] ft, int v)
    {
        int i = 0, n = ft.length;
        for(int b = Integer.highestOneBit(n);b != 0;b >>= 1){
            if((i|b) < n && ft[i|b] < v){
                i |= b;
                v -= ft[i];
            }
        }
        return i;
    }
    
    public static int[] restoreFenwick(int[] ft)
    {
        int n = ft.length-1;
        int[] ret = new int[n];
        for(int i = 0;i < n;i++)ret[i] = sumFenwick(ft, i);
        for(int i = n-1;i >= 1;i--)ret[i] -= ret[i-1];
        return ret;
    }
    
    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");
//      Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//          @Override
//          public void run() {
//              long s = System.currentTimeMillis();
//              solve();
//              out.flush();
//              if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//          }
//      };
//      t.start();
//      t.join();
    }
    
    public static void main(String[] args) throws Exception { new C().run(); }
    
    private byte[] inbuf = new byte[1024];
    public 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))){ // when nextLine, (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 int[] na(int n)
    {
        int[] a = new int[n];
        for(int i = 0;i < n;i++)a[i] = ni();
        return a;
    }
    
    private long[] nal(int n)
    {
        long[] a = new long[n];
        for(int i = 0;i < n;i++)a[i] = nl();
        return a;
    }
    
    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[][] nmi(int n, int m) {
        int[][] map = new int[n][];
        for(int i = 0;i < n;i++)map[i] = na(m);
        return map;
    }
    
    private int ni() { return (int)nl(); }
    
    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)); }
}
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