Leetcode: Minimum Moves to Equal Array Elements II

Given a non-empty integer array, find the minimum number of moves required to make all array elements equal, where a move is incrementing a selected element by 1 or decrementing a selected element by 1.

You may assume the array‘s length is at most 10,000.

Example:

Input:
[1,2,3]

Output:
2

Explanation:
Only two moves are needed (remember each move increments or decrements one element):

[1,2,3]  =>  [2,2,3]  =>  [2,2,2]

 1 public class Solution {
 2     public int minMoves2(int[] nums) {
 3         Arrays.sort(nums);
 4         int i = 0, j = nums.length-1;
 5         int count = 0;
 6         while(i < j){
 7             count += nums[j]-nums[i];
 8             i++;
 9             j--;
10         }
11         return count;
12     }
13 }

 1 public class Solution {
 2     public int minMoves2(int[] nums) {
 3         Arrays.sort(nums);
 4         int median = nums[nums.length/2];
 5         int res = 0;
 6         for (int num : nums) {
 7             res += Math.max(num-median, median-num);
 8         }
 9         return res;
10     }
11 }

 1 public class Solution {
 2     public int minMoves2(int[] nums) {
 3         int median = findMedian(nums, 0, nums.length-1, nums.length/2+1);
 4         int res = 0;
 5         for (int num : nums) {
 6             res += Math.abs(num-median);
 7         }
 8         return res;
 9     }
10     
11     public int findMedian(int[] nums, int l, int r, int k) {
12         int start = l;
13         int end = r;
14         int pivot = r;
15         while (start < end) {
16             while (start < end && nums[start] < nums[pivot]) {
17                 start++;
18             }
19             while (start < end && nums[end] >= nums[pivot]) {
20                 end--;
21             }
22             if (start == end) break;
23             swap(nums, start, end);
24         }
25         swap(nums, start, pivot);
26         if (start+1 == k) return nums[start];
27         else if (k < start+1) return findMedian(nums, l, start-1, k);
28         else return findMedian(nums, start+1, r, k);
29     }
30     
31     public void swap(int[] nums, int i, int j) {
32         int temp = nums[i];
33         nums[i] = nums[j];
34         nums[j] = temp;
35     }
36 }