[leetcode]Climbing Stairs

class Solution {
public:
int climbStairs(int n) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if(n <= 2) return n;

vector<int> f(n+1, 0);
f[1] = 1;
f[2] = 2;

for(int i = 3; i <= n; i++){
f[i] = f[i-1]+f[i-2];
}

return f
;

}
};