编辑代码

public class Main {
    public static int countWays(int n) {
        if (n == 1 || n == 2) {
            return n;
        }
        
        int[] dp = new int[n + 1];
        dp[1] = 1;
        dp[2] = 2;
        
        for (int i = 3; i <= n; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        
        return dp[n];
    }
    
    public static void main(String[] args) {
        int n = 4;
        int ways = countWays(n);
        System.out.println("Number of ways to reach " + n + " steps: " + ways);
    }
}