merge sort rust

fn main() {
    println!("{:#?}", merge_sort(&[5,4,1,6,8,2,3,7]));
}

fn merge_sort(array:  &[i32]) ->  Vec<i32>{

    if array.len() ==  1{
        return array.to_owned();
    }
    
    let mid =  array.len() / 2;
    let one_half =  &array[..mid];
    let second_half =  &array[mid..];
    
    let slice_1 =  merge_sort(one_half);
    let slice_2 = merge_sort(second_half);
    
    merge(&slice_1,  &slice_2)
    
}

fn merge(first_array: &[i32], second_array:  &[i32]) -> Vec<i32>{
    let mut temp =  Vec::new();
    let mut ptr_1 =  0;
    let mut ptr_2 =  0;
    
    while ptr_1 <  first_array.len() && ptr_2 <  second_array.len(){
        let element_1 =  first_array[ptr_1];
        let element_2 = second_array[ptr_2];
        if element_1 < element_2{
            temp.push(element_1);
            ptr_1 += 1;
        }else{
            temp.push(element_2);
            ptr_2 += 1;
        }
    }
    
    if ptr_1 <  first_array.len(){
        temp.extend(&first_array[ptr_1..]);
    }
    if ptr_2 <  second_array.len(){
        temp.extend(&second_array[ptr_2..]);
    }
    temp
}