Climbing Stairs

Question:

You are climbing a stair case. It takes n steps to reach to the top.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Solution:

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