leetcode 70. Climbing Stairs

Seawolf

斐波那契数列的应用

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?

Note: Given n will be a positive integer.

Example 1:

Input: 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps
Example 2:

Input: 3
Output: 3
Explanation: There are three ways to climb to the top.
1. 1 step + 1 step + 1 step
2. 1 step + 2 steps
3. 2 steps + 1 step

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