1.动态规划

2.初始值1,2

3.dp[i]=dp[i-1]+dp[i+1]

public class Main{
    public static void main(String[] args)
    {
        Scanner in=new Scanner(System.in);
        int num=in.nextInt();
      //动态规划
        int []dp=new int[num+1];
        dp[1]=1;
        dp[2]=1;
        for(int i=3;i<=num;i++)
        {
            dp[i]=dp[i-1]+dp[i-2];
        }
       System.out.println(dp[num]);
    }
}