10-2:跳台阶

class Solution {
public:
int jumpFloor(int number) {
if(number==1)return 1;
if(number==2)return 2;
int a=1,b=2;
for(int i=3;i<=number;i++)
{
int temp=a+b;
a=b,b=temp;
}
return b;
}
};