public class Solution {

public int climbStairs(int n) {

if(n != 1) {

int n1 = 1;

int n2 = 2;

int a = n - 2;

//f(n) = f(n-2)+f(n-1);

//return f(n);

while (a-- > 0) {

int tmp = n1;

n1 = n2;

n2 = n2 + tmp;

}**bolded text**

return n2;

}

else {

return 1;

}

}

}