classSolution{public:intclimbStairs(int n){if(n==1)return1;if(n==2)return2;int f =1, s =2, res =0;for(int i=3; i<=n; i++){
res = f + s;
f = s;
s = res;}return res;}};
數組存儲
classSolution{public:intclimbStairs(int n){
vector<int>nums(n+1);
nums[0]=1;
nums[1]=1;for(int i =2; i <= n;++i)
nums[i]= nums[i-1]+ nums[i-2];return nums[n];}};