2016-2017 CT S03E06: Codeforces Trainings Season 3 Episode 6 The Baguette Master

比赛看不懂
之后不确定题意去瞄了题解，需要分类讨论？囧
之后按照队友已经ac的题意
就是求外面一圈周长，直接可以求得

#include<bits/stdc++.h>
using namespace std;
#define sz(X) ((int)X.size())
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int N = 3e5+5;
const double pi = acos(-1.0);
const double eps = 1e-6;

int w;
int a,b,c,d,e;
double B,C1,C2,A1,A2,D;
int sgn(double x) {
    if(fabs(x) < eps) return 0;
    else if(x < 0) return -1;
    else return 1;
}
double solve(double an) {
    if(sgn(an - 2*pi) == 0) return 0;
    else {
        an /= 2;
        double ans = 0;
        ans += 2*w / tan(an);
        return ans;
    }
}

int main(){
    while(~scanf("%d",&w)) {
        double ans = 0;
        scanf("%d %d %d %d %d",&a,&b,&c,&d,&e);
        ans = a+b+c+d;
    //  printf("%.3f\n",ans);

        B = acos( (a*a+b*b-e*e)*1.0 / (2*a*b) );
        C1 = acos( (b*b+e*e-a*a)*1.0 / (2*b*e) );
        A1 = acos( (a*a+e*e-b*b)*1.0 / (2*a*e) );

        D = acos( (c*c+d*d-e*e)*1.0 / (2*c*d) );
        C2 = acos( (c*c+e*e-d*d)*1.0 / (2*c*e) );
        A2 = acos( (e*e+d*d-c*c)*1.0 / (2*e*d) );

        ans += solve(B) + solve(C1+C2) + solve(A1+A2) + solve(D);

        printf("%.3f\n",ans);
    }
    return 0;
}