设该人登上9级共走了x步一级、y步2级,z步3级
则x+2y+3z=9
x=9时,1种
x=7,y=1有C(87)=8种
x=6,z=1有C(76)7种
x=5,y=2有C(75)=21种
x=4,y=z=1有C(64)C(21)=30
x=3,y=3或x=3,z=2有C(63)+C(53)=30
X=Y=2,Z=1有C(52)C(32)=30
X=1,Y=4或x=y=1,z=2有C(51)+C(41)C(31)=17
X=0,Z=3或x=0,y=3,z=1有1+C（43）=5
故1+8+7+21+30+30+30+17+5=149种!