leetcode 189. Rotate Array

189. Rotate Array

Rotate an array of n elements to the right by k steps.
For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].
Note:
Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.
way-1:前面删一个移到后面
way-2:后面取出来往前面插

k有可能会超过数组长度，所以要处理一下。

class Solution {
public:
    void rotate(vector<int>& nums, int k) 
    {
        //way-1
        /*
        if (k == 0)
            return;
        if (k > 0)
        {   
            k = k % nums.size();
            k = nums.size() - k;
            for(int i = 1; i <= k; i++)
            {
                nums.push_back(nums[0]);
                nums.erase(nums.begin());
            }
        } 
        else
        {
            k = k % nums.size();
            k = nums.size() - k;
            for(int i=1;i<=k;i++)
            {
                nums.erase(nums.begin());
                nums.push_back(0);
            }
        }
        */
        
        //way-2
        if (k == 0)
            return;
        if (k > 0)
        {
            for (int i = 0; i < k; i++)
            {
                nums.insert(nums.begin(), nums[nums.size()-1]);
                nums.pop_back();
            }
        }
        else
        {
            k = -k;
            for (int i = 0; i < k; i++)
            {
                nums.erase(nums.begin());
                nums.push_back(0);
            }
        }
    }
};