代码（C++）：

class Solution {
public:
/**
* @param n: An integer
* @return: An integer
*/
int climbStairs(int n) {
// write your code here
// write your code here
int one = 0;
int two = 1;
while(n>0) {
two=one+two;
one=two-one;
n--;
}
return two;

}
};

爬楼梯