"pseudo code" is just a logical description of the code.
Include headers.
seed random number generator
initialize variables
LOOP ONE THOUSAND TIMES
Randomly select prize door ( 1, 2 or 3)
Randomly select first choice door ( 1, 2 or 3 )
Randomly switch choice door (switch / don't switch )
IF ( first choice is price door, AND didn't switch )
increment winFirstCount
increment winCount
ELSE IF ( first choice ISN'T prize door, AND did switch)
increment winCount
END LOOP
Output results
This is the Monty Hall problem. When you've finished, make sure that the number of wins with switching is roughly twice the number of win without switching.