Clarification on Test
          
          
            Challenges
            • Last reply from Team AlgoDaily at November 27, 2019 at 11:25PM UTC
            
          
          in the case [ 11, 13, 21, 3 ] shouldn't the answer be [ 13, 21, -1, 11 ] ? 
The first few are straight forward it seems 11 -> 13, 13 -> 21, 21 -> -1. 
For 3 we loop back to the start so 3 would map to  11 ...