一、问题描述
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?
二、思路
首先想到是用递归,但是递归超时,果断采用动态规划思想,即循环。
三、代码
class Solution {
public:
int climbStairs(int n) {
if(n <= 0)
return 0;
vector<int> step(n,0);
step[0] = 1;
step[1] = 2;
for(int i = 2;i < n;i++)
step[i] = step[i - 1] + step[i - 2];
return step[n - 1];
}
};