leetcode 70. Climbing Stairs

Seawolf

斐波那契数列的应用

1. You are climbing a stair case. It takes n steps to reach to the top.
   
2. 
   
3. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
   
4. 
   
5. Note: Given n will be a positive integer.
   
6. 
   
7. Example 1:
   
8. 
   
9. Input: 2
   
10. Output: 2
    
11. Explanation: There are two ways to climb to the top.
    
12. 1. 1 step + 1 step
    
13. 2. 2 steps
    
14. Example 2:
    
15. 
    
16. Input: 3
    
17. Output: 3
    
18. Explanation: There are three ways to climb to the top.
    
19. 1. 1 step + 1 step + 1 step
    
20. 2. 1 step + 2 steps
    
21. 3. 2 steps + 1 step

复制代码

1. class Solution {
   
2.     public int climbStairs(int n) {
   
3.         
   
4.         int[] array = new int[n+1];
   
5.         
   
6.         array[0] = 1;
   
7.         array[1] = 1;
   
8.         
   
9.         for(int i = 2 ; i <= n ; i++){
   
10.             
    
11.             array[i] = array[i -1] + array[i -2];
    
12.          
    
13.         }
    
14.         
    
15.         return array[n];
    
16.         
    
17.     }
    
18. }

复制代码