Climb stairs solution

class Solution {
    public int climbStairs(int n) {
        if (n <= 2) {
            return n;
        }

        int nCurr = 1;
        int nNext = 2;
        int swap;

        for (int i = 3; i < n; i++) {
            swap = nNext;
            nNext = nNext + nCurr;
            nCurr = swap;
        }

        return nCurr + nNext;
    }
}