Single Cycle Search

• Time : O(n)
• Space : O(1)

bool hasSingleCycle(vector<int> array) {
	int n = array.size();
	int vis = 0, idx = 0;
	while(vis < n) {
		if(vis > 0 and idx == 0) return false;
		vis++;
		idx = ((array[idx] % n) + n + idx) % n;
	}
  return idx == 0;
}