Murder Spoj Problem

Murder.java

package com.algorithms;

/**
 * @Author Mehdi Maick
 * Created on 15/09/2016.
 */

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

public class Murder {
    public static void solve(FastReader fs, PrintWriter pw) {
        int t = fs.nextInt();
        while (t-- > 0) {
            int n = fs.nextInt();
            long[] tab = fs.nextLongArray(n);
            long[] hold = tab.clone();
            Arrays.sort(tab);
            for (int i = 0; i < n; i++) {
                int pos = Arrays.binarySearch(tab, hold[i]);
                hold[i] = pos;
            }
            long sum = 0L;
            FenwickTree ft = new FenwickTree(n + 1);
            for (int i = 0; i < n; i++) {
                sum += ft.query((int) hold[i]);
                ft.update((int) hold[i] + 1, (int) tab[(int) hold[i]]);
            }
            pw.println(sum);
        }
    }

    public static void main(String[] args) throws Exception {
        FastReader fs = new FastReader(System.in);
        PrintWriter pw = new PrintWriter(new OutputStreamWriter(System.out));

        solve(fs, pw);

        fs.close();
        pw.close();
    }

    static class FastReader {

        BufferedReader reader;
        StringTokenizer st;

        FastReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream));
            st = null;
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    String line = reader.readLine();
                    if (line == null) {
                        return null;
                    }
                    st = new StringTokenizer(line);
                } catch (Exception e) {
                    throw new RuntimeException();
                }
            }
            return st.nextToken();
        }

        String nextLine() {
            String s = null;
            try {
                s = reader.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return s;
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        char nextChar() {
            return next().charAt(0);
        }

        int[] nextIntArray(int n) {
            int[] arr = new int[n];
            int i = 0;
            while (i < n) {
                arr[i++] = nextInt();
            }
            return arr;
        }

        long[] nextLongArray(int n) {
            long[] arr = new long[n];
            int i = 0;
            while (i < n) {
                arr[i++] = nextLong();
            }
            return arr;
        }

        int[] nextIntArrayOneBased(int n) {
            int[] arr = new int[n + 1];
            int i = 1;
            while (i <= n) {
                arr[i++] = nextInt();
            }
            return arr;
        }

        long[] nextLongArrayOneBased(int n) {
            long[] arr = new long[n + 1];
            int i = 1;
            while (i <= n) {
                arr[i++] = nextLong();
            }
            return arr;
        }

        void close() {
            try {
                reader.close();
            } catch (IOException e) {
                System.err.println("There's been an error trying closing the reader ");
                e.printStackTrace();
            }
        }
    }

    static class FenwickTree {

        long[] tree;

        public FenwickTree(int size) {
            tree = new long[size + 1];
        }

        public long query(int ind) {
            long sum = 0L;
            while (ind > 0) {
                sum += tree[ind];
                ind -= ind & (-ind);
            }
            return sum;
        }


        public long query(int a, int b) {
            return query(b) - query(a - 1);
        }

        public void update(int ind, int value) {
            while (ind < tree.length) {
                tree[ind] += value;
                ind += ind & (-ind);
            }
        }

        public int size() {
            return tree.length - 1;
        }


    }


}