find the kth smallest number in a list in rust

To find the kth smallest number in a list in Rust, we can follow these steps:

1. Create a vector of numbers.
2. Sort the vector in ascending order using the .sort() function.
3. Index the k-1th element of the sorted vector to get the kth smallest number.

Here's the Rust code that implements this algorithm:

main.rs
fn kth_smallest_number(numbers: &mut Vec<i32>, k: usize) -> Option<i32> {
    if k > numbers.len() {
        return None;
    }

    numbers.sort(); // Sort the vector of numbers in ascending order.
    Some(numbers[k - 1]) // Return the kth smallest number.
}

fn main() {
    let mut numbers = vec![5, 3, 8, 4, 2];
    let k = 2;
    let kth_smallest = kth_smallest_number(&mut numbers, k).unwrap();
    println!("The {}th smallest number is {}", k, kth_smallest);
}
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In this code, we define a function called kth_smallest_number that takes in a mutable vector of integers numbers and a usize k representing the kth smallest number we want to find. The function returns an Option<i32> to handle the case where the input k is larger than the length of the vector.

In the main function, we create a vector numbers and set k to 2. We then call the kth_smallest_number function and print out the result. The output of this program will be:

The 2th smallest number is 3
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