Rotate Array（leetCode189）

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

Example 1:

Input:  and k = 3
Output: 
Explanation:
rotate 1 steps to the right: 
rotate 2 steps to the right: rotate 3 steps to the right: [1,2,3,4,5,6,7][5,6,7,1,2,3,4][7,1,2,3,4,5,6][6,7,1,2,3,4,5][5,6,7,1,2,3,4]

Example 2:

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

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?

//使用雙端隊列 想怎麼幹怎麼幹 和利用的空間比較多
public static int[] rotate(int[] nums, int k) {
    // ArrayDeque, ConcurrentLinkedDeque, LinkedBlockingDeque, LinkedList
    Deque deque = new ArrayDeque();
    for (int num:nums){
        deque.add(num);
    }
    for (int j = 0;j<k;j++){

        int last = (int) deque.getLast();
        deque.removeLast();
        deque.addFirst(last);
    }
    int m = 0;
    while (deque.peek()!= null){
       nums[m] = (int) deque.pop();
       m++;
    }
    System.out.println(Arrays.toString(nums));
    return nums;

}

public static int[] rotate2(int[] nums, int k) {
    k = k % nums.length;
    int[] kHolder = new int[k];
    System.arraycopy(nums, nums.length - k, kHolder, 0, k);
    System.arraycopy(nums, 0, nums, k, nums.length - k);
    System.arraycopy(kHolder, 0, nums, 0, k);

    return kHolder;
}

public static int[] rotate3(int[] nums, int k) {
    if(k==0 || nums.length <2) {
        return nums;
    }
    int len = nums.length;
    int r = k % len;
    int[] temp = new int[len];
    for(int j=0; j<len; j++){
        temp[(j+r)%len] = nums[j];
    }
    System.arraycopy(temp, 0, nums, 0, temp.length);
    return temp;
}

題目地址：https://leetcode.com/problems/rotate-array/