A15728 | $One and Two$

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题目描述

You are given a sequence $a_1, a_2, \ldots, a_n$ . Each element of $a$ is $1$ or $2$ . Find out if an integer $k$ exists so that the following conditions are met. - $1 \leq k \leq n-1$ , and - $a_1 \cdot a_2 \cdot \ldots \cdot a_k = a_{k+1} \cdot a_{k+2} \cdot \ldots \cdot a_n$ . If there exist multiple $k$ that satisfy the given condition, print the smallest.

Each test contains multiple test cases. The first line contains the number of test cases $t$ ( $1 \le t \le 100$ ). Description of the test cases follows. The first line of each test case contains one integer $n$ ( $2 \leq n \leq 1000$ ). The second line of each test case contains $n$ integers $a_1, a_2, \ldots, a_n$ ( $1 \leq a_i \leq 2$ ).

For each test case, if there is no such $k$ , print $-1$ . Otherwise, print the smallest possible $k$ .

输入 #1

3
6
2 2 1 2 1 2
3
1 2 1
4
1 1 1 1

输出 #1

2
-1
1

C++ 编辑器

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