开始刷leetcode day18：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?

Java:

public class Solution {
    public int climbStairs(int n) {
        if(n==1) return 1;
        if(n==2) return 2;
        return climbStairs(n-1) + climbStairs(n-2);   
    } 
}

失败了，超过时间

需要使用动态规划

public class Solution {
    public int climbStairs(int n) {
        if(n==0 || n==1) return n;
       int[] result = new int[n+1];
       result[1] = 1;
       result[2] = 2;
       
       for(int i=3;i<=n;i++)
       {
           result[i] = result[i-1] + result[i-2];
       }
       
       return result[n];
    }
}