LeetCode-189: Rotate Array

189. Rotate Array

Solution

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {void} Do not return anything, modify nums in-place instead.
 */
var rotate = function (nums, k) {
    let N = nums.length;
    let startElementIndex = N - k;

    // Step 1: Normalise k, in case k is larger than N
    // console.log(`k (before)`, k);
    k = k % N;
    // console.log(`k (after)`, k);

    // Step 2: Helper function to reverse part of the array
    const reverse = (start, end) => {
        while (start < end) {
            [nums[start], nums[end]] = [nums[end], nums[start]]; // Swap
            start++;
            end--;
        }
    };

    // Step 3: Reverse the entire array
    reverse(0, N - 1);

    // Step 4: Reverse the first k elements
    reverse(0, k - 1);

    // Step 5: Reverse the remaining N-k elements
    reverse(k, N - 1);
};