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