HDU 5429 Geometric Progression

题意 : 判断 n 个数组成的序列是否为等比数列；

思路: a[i]a[i] = a[i-1]a[i+1];

代码：

import java.util.Scanner;
import java.math.*;


public class Main {
    public static void main(String args[]){
        BigDecimal a,b,c;
        Scanner cin = new Scanner(System.in);
        int t = cin.nextInt();
        while(t>0){
            t--;
            BigDecimal [] ar = new BigDecimal[110] ;
            int n = cin.nextInt();
            int cnt = 0;
            for(int i=0;i<n;i++){
                ar[i] = cin.nextBigDecimal();
                if(ar[i].equals(BigDecimal.valueOf(0)))
                     cnt ++;
            }
            if(n == 1){
                System.out.println("Yes");
                continue;
            }
            if(cnt!=0){
                if(cnt == n)
                    System.out.println("Yes");
                else
                    System.out.println("No");
                continue;
            }
            
            int flag = 1;
            for(int i=1;i<n-1;i++){
                a = ar[i].multiply(ar[i]);
                b = ar[i+1].multiply(ar[i-1]);
                if(!a.equals(b)){
                    System.out.println("No");
                    flag = 0;
                    break;
                }
            }
            if(flag == 1)
                System.out.println("Yes");
        }
    }
}