2020牛客寒假算法基础集训营5 B.牛牛战队的比赛地 (二分/三分)

https://ac.nowcoder.com/acm/contest/3006/B

三分做法

 #include<bits/stdc++.h>
 #define inf 0x3f3f3f3f
 using namespace std;
 typedef long long ll;
 typedef pair<int,int> pll;
 const int maxn=1e5+;
 const int mod =1e9+;
 const double EPS = 1e-;
 struct node
 {
     double x;
     double y;
 };
 node s[maxn];
 int n;
 double Calc(double num)
 {
     double ans=;
     for(int i=;i<=n;i++)
     {
         double q=sqrt((num-s[i].x)*(num-s[i].x)+s[i].y*s[i].y);
         if(q>ans)
         {
             ans=q;
         }
     }
     return ans;
 }
 int main()
 {
     cin >> n;
     int a,b;
     for(int i=; i<=n; i++)
     {
         cin >> a >> b;
         s[i].x=a;
         s[i].y=b;
     }
     double Left, Right;
     double mid, midmid;
     double mid_value, midmid_value;
     Left = -;
     Right = ;
     while (Left + EPS < Right)
     {
         mid = (Left + Right)/;
         midmid = (mid + Right)/;
         mid_value = Calc(mid);
         midmid_value = Calc(midmid);
         if (mid_value <= midmid_value)
             Right = midmid;
         else
             Left = mid;
     }
     cout << Calc(Left) << endl;
     return ;
 }