Wiggle sort II

class Solution {
public:
    void wiggleSort(vector<int>& nums) {
        vector <int> arr=nums;
        sort(arr.begin(),arr.end());
        int k=1,i=arr.size()-1;
        while(i>=0){
            if(k>=arr.size())k=0;  //It is must because for size 1,k=1 will give overflow.
            nums[k]=arr[i];
            k+=2;
            i--;

        }
    }
};