single.cpp

bool hasSingleCycle(vector<int> array) {  
  int numElementsVisited = 0;  
  int currentIdx = 0;  
  while (numElementsVisited < array.size()) 
  {    
    if (numElementsVisited > 0 && currentIdx == 0)      
      return false;    
    numElementsVisited++;    
    currentIdx = getNextIdx(currentIdx, array);  
  }  
  return currentIdx == 0; 
}
int getNextIdx(int currentIdx, vector<int> array) 
{  
  int jump = array[currentIdx];  
  int nextIdx = (currentIdx + jump) % (int)array.size();  
  return nextIdx >= 0 ? nextIdx : nextIdx + array.size(); 
}