Which came out of the door--the lady or the tiger?

I've been reading Life of Pi up to page 60 or so which is  full of Hindu names and this and that stories I find hard to follow. While I was googling for some information about the book, I come across this story.

This was the king's semi-barbaric method of administering justice. Its perfect fairness is obvious. The criminal could not know out of which door would come the lady; he opened either he pleased, without having the slightest idea whether, in the next instant, he was to be devoured or married. 


A princess, who is the apple of the king's eye, fell in love with a good-looking young man. This love affair moved on happily until the king happened to know about it. He was immediately imprisoned, and soon the day of his trial would come in the king's arena. 
The princess got to know the secret that behind which door the tiger/lady was. The lady was one of the fairest and loveliest, and the princess had seen the lady throwing glaces of admiration upon his lover and these glances sometimes were returned. 
The appointed day arrived. When he turned and looked at her sitting in the royal seat, their eyes met and he cast a quick, anxious glance asking the question: "Which?"
She raised her right hand. He turned and with firm, rapid steps walked toward the door on the right and opened it. Did the tiger come of of that door or did the lady?