[LEETCODE] Primary algorithm / 1.3 rotational Array array

Original title:

Given an array, the array elements to the right  k  positions, wherein  k  is non-negative.

Example 1:

Input: [1,2,3,4,5,6,7]and K = 3 
Output: [5,6,7,1,2,3,4]
Explanation: 
Rotate right Step 1: [7,1,2,3,4,5,6]
rotates two steps to the right: [6,7,1,2,3,4,5]
rotation to the right Step 3:[5,6,7,1,2,3,4]

Example 2:

Input: [-1,-100,3,99]and K 2 = 
Output: [3,99, -1, -100] 
Explanation: 
rotation to the right Step 1: [99, -1, -100,3] 
Rotate Right Step 2: [3.99, - 1 -100]

Description:

• As far as possible to come up with more solutions, there are at least three different ways to solve this problem.
• It requires space complexity is O (1) algorithm situ.

Ideas: the class talked about, a first anti, anti again one last time and then trans.

Nk digits before the first flip, then after k numbers flip it, flip it and finally the entire array:

1 2 3 4 5 6 7
4 3 2 1 5 6 7
4 3 2 1 7 6 5
5 6 7 1 2 3 4

 

class Solution {
public:
    void rotate(vector<int>& nums, int k) {
    int len = nums.size();
    if (len==1||k==0)
    {
        return ;
    }
        k=k % len;
    int n = nums.size();
        reverse(nums.begin(), nums.end()-k);
        reverse(nums.begin() + n - k, nums.end());
        reverse(nums.begin(), nums.end());
    
    
}
};