Fix typos in Problem 1
Fix typos in Problem 1

pjsinco/cs171-hw2-sinco-patrick,vivianleung/cs171-hw2-leung-vivian,Bandes/cs171-hw2-bandes-charles,vivianleung/cs171-hw2-leung-vivian,swachi/commit_graph,pjsinco/cs171-hw2-sinco-patrick,zezhouliu/cs171-hw2