public void wiggleSort(int[] nums) {

if (nums == null || nums.length <= 1) return;

int len = nums.length;

int i = 0;

while (i < len - 1) {

if ((i % 2 == 0 && nums[i] > nums[i+1]) || (i % 2 == 1 && nums[i] < nums[i+1])) swap(nums, i, i+1);

i++;

}

}

public void wiggleSort2(int[] nums) {

if (nums == null || nums.length <= 1) return;

Arrays.sort(nums);

int len = nums.length;

int mid = len / 2;

if (mid % 2 == 1) mid++;

int left = 1;

int right = mid;

while (right < len) {

swap(nums, left, right);

left += 2;

right += 2;

}

}

private void swap(int[] nums, int i, int j) {

int temp = nums[i];

nums[i] = nums[j];

nums[j] = temp;

}