Interesting algorithms (3) an array of mobile location

topic:

Given an array, the elements of the array to the right by 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 1 Step: [ 7 , 1 , 2 , 3 , 4 , 5 , 6 ] 
rotates clockwise 2 steps: [6 , 7 , 1 , 2 , 3 , 4 , 5 ] 
Rotate Right 3 steps: [ 5 , 6 , 7 , 1 , 2 , 3 , 4 ] 
Example 2 : 

Input: [ - 1 - 100 , 3 , 99 ] = and K 2 
output: [ 3 , 99 - 1 - 100 ] 
explanation: 
Rotate right 1Step: [ 99 - . 1 - 100 , 3 ] 
rotates clockwise 2 steps: [ 3 , 99 - . 1 - 100 ]

 

Array failing to issue decisions about the rotation

. 1  2  . 3  . 4 
K = 2 
integrally rotate 
. 4  . 3  2  . 1 
before rotation 2 
. 3  . 4  2  . 1 
behind the rotation of the two 
. 3  . 4  . 1  2 
achievements reached!

So the idea is very simple, first write a reverse algorithm

Then call three times a reverse algorithm on it

class Solution {
    public void rotate(int[] nums, int k) {

       if (k> nums.length) {Do not forget the critical value judgment! ! ! ! ! ! !
             % nums.length K = K;
       }

        transArray(nums,0,nums.length-1);
        transArray(nums,0,k-1);
        transArray(nums,k,nums.length-1);
    }
    public static void transArray(int[] nums, int start, int end){
        int arr_length = end + 1 - start;       
        int tmp = 0;
        for(int i=start;i<start+arr_length/2;i++){
            tmp = nums[i];
            nums[i] = nums[end-i+start];
            nums[end-i+start] = tmp;
        }
    }
}

Process derive the end-i + start there is some error.