bool checkArr(vector <int> nums){
  int numMoves=0;   //number of moves taken
  int pos=0;        //current position
  int move;         //temporary storage of current spot
  if(nums.size()==1)//if there's only one, then it's proven to always work
    return true;
  if(!nums.size())//if it's empty, say it doesn't work. Unless we say it does?
    return false;
  while( (!nums[pos]) && numMoves<nums.size() ){ //run through array
    move=nums[pos];
    nums[pos]=0; //set position to zero
    pos+=move;   //move over
    if(pos<0)    //adjust to fit inside array
      pos+=nums.size();
    pos%=nums.size();
    numMoves++;
  }
  if(pos==0 && numMoves==nums.size())
    return true;
  return false;
}