70. Climbing Stairs

class Solution {
public:
int climbStairs(int n) {
vector<int>ve;
for(int i = 0; i <= n; ++ i)
ve.push_back(0);
ve[1] = 1; ve[2] = 2;
for(int i = 3; i <= n; ++ i)
ve[i] = ve[i - 1] + ve[i - 2];
return ve
;
}
};