LeetCode-in-Rust

189. Rotate Array

Medium

Given an array, rotate the array to the right by k steps, where k is non-negative.

Example 1:

Input: nums = [1,2,3,4,5,6,7], k = 3

Output: [5,6,7,1,2,3,4]

Explanation:

rotate 1 steps to the right: [7,1,2,3,4,5,6]

rotate 2 steps to the right: [6,7,1,2,3,4,5]

rotate 3 steps to the right: [5,6,7,1,2,3,4]

Example 2:

Input: nums = [-1,-100,3,99], k = 2

Output: [3,99,-1,-100]

Explanation:

rotate 1 steps to the right: [99,-1,-100,3]

rotate 2 steps to the right: [3,99,-1,-100]

Constraints:

• 1 <= nums.length <= 105
• -231 <= nums[i] <= 231 - 1
• 0 <= k <= 105

Follow up:

• Try to come up with as many solutions as you can. There are at least three different ways to solve this problem.
• Could you do it in-place with O(1) extra space?

Solution

impl Solution {
    pub fn rotate(nums: &mut Vec<i32>, k: i32) {
        let mut rotated = vec![0; nums.len()];
        let k_fixed = k as usize % nums.len();

        for (i, item) in nums.iter().enumerate() {
            match nums.get(i+k_fixed) {
                Some(n) => rotated[i+k_fixed] = *item,
                None => rotated[(i+k_fixed)-nums.len()] = *item,
            }
        }
        nums.copy_from_slice(&rotated)
    }
}

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