Team Contests - Warmup Problem C

Problem C

Problem Description

Definite an operation work(Q,x) as sequence Q from the first number on,keep the top x numbers and delete followed x numbers, keep the next x numbers and delete followed x numbers, then keep recycling this process.

Q is the positive integer sequence, Given a sequence A, operating Work(Q,Ai) upon positive integer sequence output the nth member after n operations.

Input

First line contains T(T≤10) denoting the number of test cases.

  T cases follows. For each cases: 

  First line contains integer n(0<n≤10000), next line contains n integers Ai(0<Ai≤1000) indicates the i-th operation.

Output

For each case output the answer in one line.

Sample Input

2
3
1 2 3
3
3 2 1

Sample Output

9
15

从后往前推出公式,但是会爆longlong,用java写就好了。

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

public class Main {
    static int[] a; 
    public static void main(String args[]) {
        Scanner cin = new Scanner(System.in);
        int t = cin.nextInt();
        while(t-->0) {
            a = new int[10010];
            int n = cin.nextInt();
            for(int i = 1; i <= n; i++) a[i] = cin.nextInt();
            BigInteger ans = BigInteger.valueOf(n);
            for(int i = n; i >= 1; i--) {
                int tmp = 0;
                if(ans.mod(BigInteger.valueOf(a[i])).compareTo(BigInteger.ZERO) == 0) tmp = 1;
                BigInteger tmp2 = ans.divide(BigInteger.valueOf(a[i])).subtract(BigInteger.valueOf(tmp));
                ans = ans.add(tmp2.multiply(BigInteger.valueOf(a[i])));
            }
            System.out.println(ans);
        }
    }
}