[LintCode] Climbing Stairs 爬梯子问题

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?

Have you met this question in a real interview?

Yes

Example

Given an example n=3 , 1+1+1=2+1=1+2=3

return 3

LeetCode上的原题，请参见我之前的博客Climbing Stairs。

解法一：

class Solution {
public:
    /**
     * @param n: An integer
     * @return: An integer
     */
    int climbStairs(int n) {
         ) ;
         vector<int> dp(n);
         dp[] = ; dp[] = ;
         ; i < n; ++i) {
             dp[i] = dp[i - ] + dp[i - ];
         }
         return dp.back();
    }
};

解法二：

class Solution {
public:
    /**
     * @param n: An integer
     * @return: An integer
     */
    int climbStairs(int n) {
        , b = ;
        while (n--) {
            b += a;
            a = b - a;
        }
        return a;
    }
};