#include <iostream> using namespace std; int main() { int dp[90] = {0}; //记录中间状态 //店铺[i]表示到第i级台阶的方案数 dp[1] = 1; dp[2] = 2; int n; scanf("%d", &n); for (int i = 3; i <= n; i++) { dp[i] = dp[i - 1] + dp[i - 2]; } printf("%d\n", dp[n]); return 0; } // 64 位输出请用 printf("%lld")