Wiggle Sort

Source

• leetcode: 280

Given an unsorted array nums, reorder it in-place such that
nums[0] <= nums[1] >= nums[2] <= nums[3]....

For example, given nums = [3, 5, 2, 1, 6, 4], one possible answer is
[1, 6, 2, 5, 3, 4].

Java

void wiggleSort(vector<int>& nums) {
    int flag = 1;
    for (int i = 1; i < nums.size(); ++i) {
        if (nums[i] * flag < nums[i-1] * flag){
            swap(nums[i], nums[i-1]);
        }
        flag = -flag;
    }
}