Guidance on the use of pins of LM1117
It is literally on page 3 of the datasheet, which you linked in the question.



Where exactly is the confusion? It states very clearly that Adj/GND in the SOT-223 is pin 1. Vin pin 3, and Vout is pins 2 and 4. 

There should be no need to double check if you read this table. Remember the input and output capacitors.