题目描述
Ehab loves number theory, but for some reason he hates the number $x$. Given an array $a$, find the length of its longest subarray such that the sum of its elements isn't divisible by $x$, or determine that such subarray doesn't exist.
An array $a$ is a subarray of an array $b$ if $a$ can be obtained from $b$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end.
Input
The first line contains an integer $t$ $(1 \le t \le 5)$ — the number of test cases you need to solve. The description of the test cases follows.
The first line of each test case contains 2 integers $n$ and $x$ ($1 \le n \le 10^5$, $1 \le x \le 10^4$) — the number of elements in the array $a$ and the number that Ehab hates.
The second line contains $n$ space-separated integers $a_1$, $a_2$, $\ldots$, $a_{n}$ ($0 \le a_i \le 10^4$) — the elements of the array $a$.
Output
For each testcase, print the length of the longest subarray whose sum isn't divisible by $x$. If there's no such subarray, print $-1$.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
样例输出
提示
In the first test case, the subarray $[2,3]$ has sum of elements $5$, which isn't divisible by $3$.
In the second test case, the sum of elements of the whole array is $6$, which isn't divisible by $4$.
In the third test case, all subarrays have an even sum, so the answer is $-1$.