1 #include <stdio.h> 2 #include <string.h> 3 #include <stdlib.h> 4 #include <math.h> 5 #include <ctype.h> 6 #include <map> 7 #include <set> 8 #include <string> 9 #include <vector>10 #include <queue>11 #include <stack>12 #include <list>13 #include <algorithm>14 #include <iostream>15 #define PI acos( -1.0 )16 using namespace std;17 typedef pair<int,int> P;18 typedef long long ll;19 const double E = 1e-7;20 21 const double g = 9.8;22 double h, v;23 24 double dis( double x )25 {26     double ans = v*cos(x)*( sqrt( 2.0*h*g + v*v*sin(x)*sin(x) ) + v*sin(x) ) / g;27     return ans;28 }29 30 int main()31 {32     int T;33     scanf( "%d", &T );34     while( T-- )35     {36         scanf( "%lf%lf", &h, &v );37         double r, l;38         double legth = 0;39         r = PI / 2.0;40         l = 0;41         while( r-l > E )42         {43             double mid =  l + ( r-l ) / 3;44             double midmid = r - ( r-l ) / 3;45             double ans1 = dis( mid );46             double ans2 = dis( midmid );47             if( ans1 < ans2 ) {l = mid; legth = max( legth, ans2 ); }48             else { r = midmid; legth = max( legth, ans1 ); }49         }50         printf( "%.2lf\n", legth );51     }52     return 0;53 }