Rotate Array

Leetcode Problem 189: Rotate Array

Problem Summary

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

Techniques

• Reverse the entire array
• Reverse the first k elements
• Reverse the remaining elements

Solution

function rotate(nums: number[], k: number): void {
    const kModulo = k % nums.length

    for(let i = 0, j = nums.length - 1; i < j; i++, j--) {
        [nums[i], nums[j]] = [nums[j], nums[i]]
    }

    for(let i = 0, j = kModulo - 1; i < j; i++, j--) {
        [nums[i], nums[j]] = [nums[j], nums[i]]
    }

    for(let i = kModulo, j = nums.length - 1; i < j; i++, j--) {
        [nums[i], nums[j]] = [nums[j], nums[i]]
    }
}

const example = [1,2,3,4,5,6,7]
rotate(example, 3)

console.log(example)