189. Rotate Array

Problem Statement

Given an integer array nums, 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

Intuition

Checkout this brilliant way of rotating array
 //     1 2 3 4
    //     rotate by 3 right

        
    //    reqiured ans= 2 3 4 1

    //     reverse1= 4 3 2 1
    //     reverse2= (4 3 2) 1 = 2 3 4 1
    //     reverse3= 2 3 4 (1) = 2 3 4 1   final ans

Links

https://leetcode.com/problems/rotate-array/

Video Links

Approach 1:

Reverse 

C++

class Solution {
public:
    void rotate(vector<int>& nums, int k) {
        k=k%nums.size();

        reverse(nums.begin(),nums.end());
        reverse(nums.begin(),nums.begin()+k);
        reverse(nums.begin()+k,nums.end());
    }
};

Approach 2:

C++

Approach 3:

C++

Approach 4:

C++

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