Hdu2199 can you solve this equation? & Hdu2899 strange fuction & hdu1551cable Mast

Obviously, you can perform binary search. Pay attention to the accuracy.

I know two ways to write binary statements. Pay attention to loop control.

First

# Include <iostream>
# Include <algorithm>
# Include <math. h>
 Using   Namespace STD;
 Double Cal ( Double X)
{
 Return   8 * X + 7 * X + 2 * X +3 * X + 6 ;
}
 Int Main ()
{
 Double Y;
 Int T;
Scanf ( "  % D  " , & T );
 While (T --)
{
Scanf ( "  % Lf " , & Y );
 If (Y <CAL ( 0 ) | Y> CAL ( 100 ))
{
Printf ( "  No solution! \ N  " );
 Continue ;
}
 Double Left = 0 , Right = 100 ;
While (Left <right)
{
 Double Mid = (left + right )/ 2.0 ;
 Double Temp = CAL (MID );
 If (FABS (temp-y) <= 1E- 6 )
{
Printf ( "  %. 4f \ n  " , Mid );
 Break ;
}
 Else   If (Temp> Y)
Right = mid;
 Else Left = mid;
}
}
 Return   0 ;
}

Second

# Include <iostream>
# Include <math. h>
 Using   Namespace STD;
Double Y = 0 ;
 Double Cal ( Double X)
{
 Return   8 * X + 7 * X + 2 * X + 3 * X + 6 ;
}
 Int Main ()
{
Int T;
Scanf ( "  % D  " , & T );
 While (T --)
{
Scanf ( "  % Lf  " , & Y );
 If (CAL ( 0 )> Y | CAL ( 100 ) <Y)
{
Printf ( "  No solution! \ N  " );
 Continue ;
}
 Double Left = 0.0 , Right = 100.0 ;
 While (Right-left> 1E- 6 )
{
 Double Mid = (left + right )/2.0 ;
 Double Temp = CAL (MID );
 If (Temp> Y)
Right = mid-1E- 6 ;
 Else  
Left = Mid + 1E- 6 ;
}
Printf ( "  %. 4lf \ n  " , (Left + right )/ 2.0 );
}
 Return   0 ;
}

Hdu2899 follows a similar question, but it is okay to first find the guide.

Hdu2899

# Include <iostream>
# Include <algorithm>
# Include <math. h>
 Using   Namespace STD;
 Double Y;
 Double Cal ( Double X)
{
Return   42 * POW (X, 6 ) + 48 * POW (X, 5 ) + 21 * X + 10 * X;
}
 Double FX ( Double X)
{
 Return   6 * POW (X, 7 ) +8 * POW (X, 6 ) + 7 * POW (X, 3 ) + 5 * X-y * X;
}
 Int Main ()
{
 Int T;
Scanf ( "  % D  " , & T );
 While (T --)
{
Scanf ( "  % Lf  " , & Y );
 Double Left = 0 , Right = 100 , Temp;
 While (Left <right)
{
 Double Mid = (left + right )/ 2.0 ;
Temp = CAL (MID );
 If (FABS (temp-y) <= 1E- 5 )
{
Printf ( "  %. 4f \ n  " , FX (MID ));
 Break ;
}
 Else   If (Temp <Y)
Left = mid;
 Else Right = mid;
}
}
 Return   0 ;
}

Hdu1551 cable master

How many cables are known, and the number of equal cables to be cut, and the maximum length of the cut Cables

If the length of the obtained cable is less than 0.01, the output is 0.0

Analysis: the length of the cable to be split into two parts can be approached.

Hdu1551

# Include <iostream>
# Include <math. h>
# Include <algorithm>
 Using   Namespace STD;
 Int N, K;
 Double A [ 10001 ], Maxlen;
 Int Cal (Double C)
{
 Int T = 0 ;
 For ( Int I = 0 ; I <n; I ++)
T + = ( Int ) (A [I]/C );
 Return T;
}
 Int Main ()
{
 While (Scanf ("  % D  " , & N, & K) = 2 & (N | K ))
{
Maxlen = 0.0 ;
 For ( Int I = 0 ; I <n; I ++)
{
Scanf ( "  % Lf  " , & A [I]);
Maxlen = max (maxlen, a [I]);
}
 Double Left = 0.01 , Right = maxlen, mid;
 While (Right-left> 1E- 5 )
{
Mid = (left + right )/ 2 ;
 Int T = CAL (MID );
 If (T> = K)
Left = mid;
 Else Right = mid;
}
 Int T = CAL (left );
 If (T> = K)
Printf ( "  %. 2f \ n  " , Left );
 Else Printf ( "  0.0 \ n  " );
}
 Return   0 ;
}