LeetCode 70. Climbing Stairs

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?

很明显看出这是个斐波那契数列，但是我们一般不用递归的方法，而采用循环来求解

 

class Solution {
public:
    int climbStairs(int n) {
        if (n < 1)return 0;
		vector<int> vec(n+1, 0);
		vec[0] = 1;vec[1] = 1;
		for (int i = 2;i <= n;++i)
		{
			vec[i] = vec[i - 1] + vec[i - 2];
		}
		return vec[n];
    }
};