Given an integer array `nums`

and a positive integer `k`

, return *the most competitive subsequence of *

`nums`

`k`

.An array's subsequence is a resulting sequence obtained by erasing some (possibly zero) elements from the array.

We define that a subsequence `a`

is more **competitive** than a subsequence `b`

(of the same length) if in the first position where `a`

and `b`

differ, subsequence `a`

has a number **less** than the corresponding number in `b`

. For example, `[1,3,4]`

is more competitive than `[1,3,5]`

because the first position they differ is at the final number, and `4`

is less than `5`

.

**Example 1:**

Input:nums = [3,5,2,6], k = 2Output:[2,6]Explanation:Among the set of every possible subsequence: {[3,5], [3,2], [3,6], [5,2], [5,6], [2,6]}, [2,6] is the most competitive.

**Example 2:**

Input:nums = [2,4,3,3,5,4,9,6], k = 4Output:[2,3,3,4]

**Constraints:**

`1 <= nums.length <= 10`

^{5}`0 <= nums[i] <= 10`

^{9}`1 <= k <= nums.length`

```
struct Solution;
impl Solution {
fn most_competitive(nums: Vec<i32>, k: i32) -> Vec<i32> {
let n = nums.len();
let k = k as usize;
let mut arr = vec![];
let mut m = 0;
for i in 0..n {
while let Some(&top) = arr.last() {
if top > nums[i] && k < n - m {
m += 1;
arr.pop();
} else {
break;
}
}
arr.push(nums[i]);
}
arr[0..k].to_vec()
}
}
#[test]
fn test() {
let nums = vec![3, 5, 2, 6];
let k = 2;
let res = vec![2, 6];
assert_eq!(Solution::most_competitive(nums, k), res);
let nums = vec![2, 4, 3, 3, 5, 4, 9, 6];
let k = 4;
let res = vec![2, 3, 3, 4];
assert_eq!(Solution::most_competitive(nums, k), res);
}
```