# include<iostream> # include<cmath> # include<cstdio> # include<cmath> //平方根 # include<cstdlib> //随机数 # include<ctime> using namespace std; int main(){ int n,a[4],i; cin>>n; for (i=1;i<=4;i++){ cin>>a[i]; } if (a[2]-a[1]!=a[3]-a[2]){ cout<<a[1]*pow(a[2]/a[1]*1.0,n-1); } else{ cout<<a[1]+(a[2]-a[1])*(n-1); } return 0; } 评论: