Advanced stair climbing

subject ：

Suppose you're climbing the stairs . need n You can reach the top of the building .

Every time you climb 1 or 2 A stair . How many different ways can you climb to the top of the building ？

Be careful ： Given n Is a positive integer .

Example 1： Input ： 2 Output ： 2 explain ： There are two ways to climb to the top .

1 rank + 1 rank
2 rank
Example 2： Input ： 3 Output ： 3 explain ： There are three ways to climb to the top .

1 rank + 1 rank + 1 rank
1 rank + 2 rank
2 rank + 1 rank

Code ：

class Solution {
    public int climbStairs(int n) {
        int[] dp = new int[n+1];
        int[] weight = {1, 2};
        dp[0] = 1;

        for(int i = 0; i <= n; i++){
            for(int j = 0; j < weight.length; j++){
                if(i >= weight[j]){
                   dp[i] += dp[i-weight[j]];
                }
            }
        }
        return dp[n];
    }
}