Solving shuffle the array problem on leetcode in Rust

Question

fn shuffle(nums: Vec<i32>, n: i32) -> Vec<i32> {
    let mut res: Vec<i32>;
    let mut i = 0;

    while i < n {
        res.push(nums[i]);
        res.push(nums[n + i]);
        i += 1;
    }

    res
}

When I try to index the nums array to get a value at [i], I get this error:

the type [i32] cannot be indexed by i32
the trait SliceIndex<[i32]> is not implemented for i32
required because of the requirements on the impl of Index<i32> for Vec<i32>

Any ideas how to solve this?

Answer 1

You can only index Vec using usizes, so you have to cast your i32s to usizes in order to index into nums:

fn shuffle(nums: Vec<i32>, n: i32) -> Vec<i32> {
    let mut res = Vec::new();
    let mut i = 0;

    while i < n {
        res.push(nums[i as usize]);
        res.push(nums[(n + i) as usize]);
        i += 1;
    }

    res
}

playground