[leetcode] #70 Climb stairs

這題很簡單, 題目要求給n個階梯, 若每次僅走一步或兩步, 則走到第n階的路徑有多少種。

(思路)
1. 第 i-th 階 step[i] 儘可能從 step[i-1] 或 step[i-2] 出發.
2. 要留意 1st 跟 2rd 階的算法

1:  public class Solution {  
2:    public int climbStairs(int n) {  
3:      if (n<=0)  
4:        return 0;  
5:      int[] steps = new int[n+1];  
6:      steps[0] = 1;  
7:      steps[1] = 1;  
8:      for (int i=2;i<=n;i++) {  
9:        steps[i] = steps[i-1] + steps[i-2];  
10:      }  
11:      return steps[n];      
12:    }  
13:  }