LOJ P10016 灯泡题解

每日一题 day50 打卡

Analysis

用初中学的相似推一波式子，再用三分一搞就好了。

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #define int long long
 6 #define rep(i,s,e) for(register int i=s;i<=e;++i)
 7 #define dwn(i,s,e) for(register int i=s;i>=e;--i)
 8 using namespace std;
 9 inline int read()
10 {
11     int x=0,f=1;
12     char c=getchar();
13     while(c<'0'||c>'9') {if(c=='-') f=-1; c=getchar();}
14     while(c>='0'&&c<='9') {x=x*10+c-'0'; c=getchar();}
15     return f*x;
16 }
17 inline void write(int x)
18 {
19     if(x<0) {putchar('-'); x=-x;}
20     if(x>9) write(x/10);
21     write(x%10+'0');
22 }
23 int T;
24 double H,h,D;
25 double L1,L2;
26 double calc(double x)
27 {
28     double dis=(double)(H*x)/(double)(H-h);
29 //    cout<<"dis:"<<dis<<" "<<"fz:"<<(double)(H*x)<<" "<<"fm:"<<(double)(H-h)<<" x:"<<x<<endl;
30     if(dis<=D) return dis-x;
31     else 
32     {
33         L1=(double)(D-x);
34         L2=((double)(D*h)-(double)(L1*H))/(double)(D-L1);
35         return L1+L2;
36     }
37 }
38 signed main()
39 {
40     T=read();
41     while(T--)
42     {
43         scanf("%lf%lf%lf",&H,&h,&D);
44         double l=0.0,r=D;
45         while(r-l>=1e-11)
46         {
47             double mid1=l+(r-l)/3,mid2=r-(r-l)/3;
48 //            cout<<"l:"<<l<<" "<<"r:"<<r<<" "<<"mid1:"<<mid1<<" "<<"mid2:"<<mid2<<endl;
49             if(calc(mid1)<=calc(mid2)) l=mid1;
50             else r=mid2;
51 //            system("pause");
52         }
53         printf("%.3lf
",calc(l));
54     }
55     return 0;
56 }

请各位大佬斧正~~（反正我不认识斧正是什么意思）~~

LOJ P10016 灯泡 题解

Analysis

LOJ P10016 灯泡题解