liujunhao 2023-12-19 18:55:40 5 返回题目
#include<bits/stdc++.h>
using namespace std;
int main(){
double n; cin>>n; if(n>=0&&n<5)n=-n+2.5; else if(n>=5&&n<10)n=2-(1.5*(n-3)*(n-3)); else if(n>=10&&n<20)n=n/2-1.5; printf("%.3f", n); return 0;
}
