class Solution {
public void wiggleSort(int[] nums) {
// 1. If i is even, then nums[i] <= nums[i - 1].
// 2. If i is odd, then nums[i] >= nums[i - 1].
for (int i = 1; i < nums.length; ++i)
if ((i % 2 == 0 && nums[i] > nums[i - 1]) || (i % 2 == 1 && nums[i] < nums[i - 1]))
swap(nums, i, i - 1);
}
private void swap(int[] nums, int i, int j) {
final int temp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
}
}