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 <= 0) {
return 0;
}
vector<int> fb(n + 1, 1);
fb[2] = 2;
for (int i = 3; i <= n; ++i) {
fb[i] = fb[i - 1] + fb[i - 2];
}
return fb
;
}
};