## 1673. Find the Most Competitive Subsequence

Given an integer array `nums` and a positive integer `k`, return the most competitive subsequence of `nums` of size `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 = 2
Output: [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 = 4
Output: [2,3,3,4]
```

Constraints:

• `1 <= nums.length <= 105`
• `0 <= nums[i] <= 109`
• `1 <= k <= nums.length`

## Rust Solution

``````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);
}
``````

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