剑指offer--跳台阶

class Solution {
public:
int jumpFloor(int number) {
int a[] = {0,1,2};
if(number<=2)
return a[number];
int last1 = a[2];
int last2 = a[1];
int sum = 0;
for(int i=3; i<= number; i++){
sum = last1 + last2;
last2 = last1;
last1 = sum ;
}

return sum;
}
};