find the kth largest element in an array in rust

One way to find the kth largest element in an array is to sort the array in descending order and then return the element at index k-1. Here's one way to implement this in Rust:

main.rs
fn kth_largest_element(arr: &[i32], k: usize) -> Option<i32> {
    if k > arr.len() {
        return None;
    }
    
    let mut sorted_arr = arr.to_vec();
    sorted_arr.sort_by(|a, b| b.cmp(a)); // sort in descending order
    
    Some(sorted_arr[k-1])
}
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This function takes an immutable reference to an array (&[i32]) and a k value specifying the position of the desired element. It returns an Option<i32> which is Some if k is within the bounds of the array, and None otherwise.

Inside the function, we first check if k exceeds the length of the array. If so, we return None.

Next, we create a mutable copy of the input array using to_vec(), which allocates a new vector of the same size as the array and copies its elements into it. We then sort the copy using sort_by() and a closure that compares elements in descending order.

Finally, we use Some() to return the element at position k-1 of the sorted copy.