Rotate Array

Desicription

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

Example 1:

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Input: [1,2,3,4,5,6,7] and 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:

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Input: [-1,-100,3,99] and 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]

Note:

  • Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.
  • Could you do it in-place with O(1) extra space?

Solution

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class Solution {
private:
void fun(vector<int>& nums, int left, int right) {
if(left >= right)
return ;
while(left <= right) {
swap(nums[left], nums[right]);
left++;
right--;
}
}
public:
void rotate(vector<int>& nums, int k) {
k = k % nums.size();
fun(nums, 0, nums.size() - 1);
fun(nums, 0, k - 1);
fun(nums, k, nums.size() - 1);
}
};