BC - Geometric Progression (等比数列的性质 + java大数)

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Geometric Progression Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 421    Accepted Submission(s): 118 Problem Description Determine whether a sequence is a Geometric progression or not. In mathematics, a **geometric progression**, also known as a **geometric sequence**, is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed, non-zero number called the common ratio. For example, the sequence 2, 6, 18, 54, ... is a geometric progression with common ratio 3. Similarly 10, 5, 2.5, 1.25, ... is a geometric sequence with common ratio 1/2. Examples of a geometric sequence are powers  rk  of a fixed number r, such as  2k  and  3k . The general form of a geometric sequence is a, ar, ar2, ar3, ar4, … where r ≠ 0 is the common ratio and a is a scale factor, equal to the sequence's start value.   Input First line contains a single integer  T(T≤20)  which denotes the number of test cases.  For each test case, there is an positive integer  n(1≤n≤100)  which denotes the length of sequence,and next line has  n  nonnegative numbers  Ai  which allow leading zero.The digit's length of  Ai  no larger than  100 .   Output For each case, output "Yes" or "No".   Sample Input 4 1 0 3 1 1 1 3 1 4 2 5 16 8 4 2 1   Sample Output Yes Yes No Yes   Source import java.util.*; import java.math.*; import java.io.*; public class Main{ static final int MAXN = 100 + 5; static Scanner cin = null; static PrintStream cout = null; static BigInteger [] A = new BigInteger[MAXN]; public static void main(String [] agrs){ cin = new Scanner(System.in); cout = new PrintStream(System.out); int T, n; int Have0, All0; T = cin.nextInt(); while(T -- > 0){ Have0 = All0 = 0; n = cin.nextInt(); for(int i = 0;i < n;i ++){ A[i] = cin.nextBigInteger(); if(A[i].equals(BigInteger.ZERO)) { Have0 ++; All0 ++; } } boolean flag = true; for(int i = 0;i < n - 2;i ++){ if(!A[i].multiply(A[i + 2]).equals(A[i + 1].pow(2))){ flag = false; break; } } if(n > All0 && Have0 > 0) flag = false; if(flag) cout.println("Yes"); else cout.println("No"); } } }