10-26 Exercise 3: Find roots of a quadratic equation

Question

Write a program to find roots of a quadratic equation

A quadratic equation is a second order equation having a single variable. Any quadratic equation can be represented as where a, b and c are constants ( a can't be 0) and x is unknown variable. 

寫一個找二次方程的求根程式

For Example

 is a quadratic equation where a, b and c are 2, 5 and 3 respectively.

To calculate the roots of quadratic equation we can use below formula. There are two solutions of a quadratic equation.

使用下列公式:

x = (-b + sqrt(D))/(2*a)
x = (-b - sqrt(D))/(2*a)

where, D = (b*b-4*a*c) is Discriminant (判別式), which differentiate the nature of the roots of quadratic equation.

For the complex result (複數根):

realPart = -b/(2*a);
imaginaryPart =sqrt(-D)/(2*a);

Note: We have used sqrt() function to find square root which is in math.h library.

 

Example input 1:

1 2 1

Example output 1:

Roots of 1.00x^2 + 2.00x + 1.00 = 0 are real and same
x1 = x2 = -1.00

 

Example input 2:

1 -3 2

Example output 2:

Roots of 1.00x^2 + -3.00x + 2.00 = 0 are real and different
x1 = 2.00
x2 = 1.00

 

Example input 3:

1 2 2

Example output 3:

Roots of 1.00x^2 + 2.00x + 2.00 = 0 are complex and different
x1 = -1.00+1.00i
x2 = -1.00-1.00i

Comments

We will continue this question in few days

---

Everything is fixed. Enjoy your time with The Judge :)

---

ANNNNNNNNNNNNNNNNNNNNNNNNNNGRYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

---

Your code has newline at the end sometime. You learned this lesson many times!

---

After i correct the newline in my code,there is still wrong output.However,I had run the program in Codeblocks.The output is still as well as the result. Seeking for help.

---

your output lack of 1 space at line 8 when print out "Roots of ...". Please be careful with all small details when working with online judge

Answer 1

Hidden content!
* **** * ** *   *  * ** * 
 * * ***    *    *** 

int main() {
*** *  * *   * * *   * ****** * **   * *
*    **   * *** ***      **  *    *** %f   ** ***  * &a, &b,  *  *
 ** *  **  ** * ** ** * * *****
* ****  ***** **   ***** * * *    * *  {
* *  **** * * * *  *    * ****  * **  ***     *****   * ** **** of %.2fx^2 + %.2fx + %.2f = 0 are complex and  ***  =  * * * ***  *  = *** *  * * * *  a, b, c, (-b)/(2*a), **     ****   (-b)/(2*a), *  ** * ** *
**  **   * * *****  ** *** 
*   * * ***    *****        if(d==0) {
*  * ****   *  * * **       *   ***  **  * * * * *     ***** ** 
 *  **   *  *****   **    ** **** * *** *** * **  * *****   ***** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = * * *     a, b, c, x1);
    *  ** * ** * * ***  **  **
*   * ****  * *    * ** *   *    * *   * {
   * *   *** **** **  *** *    *  *** *** ** *  * **          *   *
  * *   *** * **  * * *   **  ****     *****  ****   ***** * ** 
   * *  *****   *  * ******* * **  *  * *  ****  *  * *  * *  * ** * ** of %.2fx^2 + %.2fx + %.2f = 0 are real and  * **    = %.2f\nx2 = ****  * *  * * a, b, c, x1, x2);
** * *  ** * * * ***  ** *
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

Hidden content!
#include ***** ***  **
*  *      *  *** * ***
#include *** * *  **   *** 

int main()
{
 ** *****  * * ***** **     ******    ****** * 
* ***  * **   *****  *   * ****** *        %f * *   *  *   **    **** ****
* **** *** * **  **   ** *  * ** **
** **** * *** * *   *  * *        * ****   
   * *    * ** ** **** ***   * *     **
  *   *** * *  *** *  **  ***  *  **
**  ** *   * * *   *** * *  **     ** *   of %.2fx^2 + %.2fx + %.2f = 0 are real and *     = %.2f\nx2 = * *  ***    **** **  **
*  * *  * * ** **** **  * **   *  *  if(D==0)
     **  **   * * * *     * **   **** * * ** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 =  *******  *     
 ** *       ***  * *   ******  
  ****** *     ***        *  ** * * *  *  ***   of %.2fx^2 + %.2fx + %.2f = 0 are complex and   * ** * =   ***** * = * * ****  *   ** ****** **   ******* *****        ** 
 ***    * **         ****   **** 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

Hidden content!
#include  **** * ***  
** *      ***   * *  ***  *
*   *  ***** ****  *

int main()
{
         ***  * ***   ***  ****  *  ** * 
     *****      ***  *******      %f ***** **      * * ***  * 
*  ***   ** ***     * ** **  * *  ****
*     **    **** * **   * *  *  ***   *** 
 ** **  * *        ****  ******       
 **     *  *** **    ****  *   **     
***   **** * *  * *   *** * *****   **   **** of %.2fx^2 + %.2fx + %.2f = 0 are real and  **  ** = %.2f\nx2 =  * ***  *   **  * 
 *  ****   *  ***   ** ***  **  
** * * *** * ***       * *** ** * * * ** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 =   ********* ***   *  
* * * *** * ***  *******  **
****  * **    *  ****    ** *    *** **  **  * * * of %.2fx^2 + %.2fx + %.2f = 0 are complex and *   *  *  = %.2f + **  * = %.2f - *  *  **   *****   ** ** *******  *   *  ** *  *** * 
*  ** *  **    *  * ** * * ** ** * 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output

Answer 4

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include<math.h>
int main()
{
****    * *    *** *   a,b,c,x1,x2,D;
 *   ** *  *  * * *       * ** *** * **** %f *   ***  *****  * **  *   ****
** * * **** * *  *    * ****** ***** * *
   *** ** **  * * * * *   **   = (-b + sqrt(D))/(2*a);
*  *  * * *     *   ** *  *  = (-b - sqrt(D))/(2*a);
 **** * ** * **    **    *  ****  *
**    * * *  ** * ** ***** **  **   **    ***    * *
*  ** *  * ***      **  * *** ***   ** * **  ***  ** * * * ****   **     **  **** * * * * of %.2fx^2 + %.2fx + %.2f = 0 are real and different\n",a,b,c);
 **   ***  ** *  *** * * *      *** *    *  * *  *   *  **   **   **   *  * *** * * ***   * *  * = %.2f\n",x1);
**  *  *    *   * * ******* ** **** * ** **  *  *  **  *** ** * * *    *    *   * * ****  **** ** = %.2f",x2);
 ** * *** ** *** * * *** **  * *  *    * **** 
** ***  **  ***   *   * * *    if(D==0)
 *  * **     ****    **    *     *  *** * **    ****
* *  **    **  **  ***    * *   **  **   **   *     * ****** *  * * ** *   ****** * ** * *** **  *    of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
* * *    *  ****  * **  **  *  * ***  ***** **  *    * * *    ** **    ** ***  **    * = x2 = %.2f",x1);
   * ****  * * *****  * **  *   * ** *   *  * **  * *   *
 **** *****  *** ******* ***  
  *  *** * *** **   ***** ***   ** * ** * *    *  *  
 *** **   *   **  * * * ** *       *   ***   ****** * **    ****  * * *    ** * * ***    * ** *  * of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\n",a,b,c);
 ***  *  **   *   * * ***      ** ** *   **       *  * * ** *   ***** *  *** * * * * *  * * * *     = *** *    * * ***  ** **      ***
  *  *** *       **  *  *** **** **  * * *    * * * **   ***  *  * * **  * *   *** **       ** *  =        ***** *******        
* **  ** *  * *      *  **** **     *******  **   * * *
  * * *  * ***** * **  * ***  * ** 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 5

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include<math.h>
int main()
{
*   ****  * * ****     *** * a,b,c,x1,x2,D;
  ** ****  * *   ***** ** **    **  *         * %f    *  ****** **  ** *   * **  *
*  *  ** *    **** ** * *   ***     *
 ******** ***  *  *  = (-b + sqrt(D))/(2*a);
   ** ** ** * * * * ** *    = (-b - sqrt(D))/(2*a);
* *** **  * *  **      **   *** *
** * *    * **  * ***  **  ** ** *    * *  **     *
*  *** **** *    ***** *  ******* **   *  * * * * * ***** ** **  *     *   *  **  * *  **** * *** of %.2fx^2 + %.2fx + 1.00 = 0 are real and different\n",a,b,c);
**  ******   *  *   *  ** *  *      * * *****   * **  ****  ***   ****  * = %.2f\n",x1);
 *** **** ****     ***  * *    * ** *   ** ** *** * * * *   *   ***   ** * *  *  * ** *  *   = %.2f",x2);
**  ***** ***    **  ** **      * * * * ** **  ** * *  *
**  *    ** ******  *  **** *  if(D==0)
  * * ***   *   *  ** ** **     * * **   * ***  * * *   * * 
* ***** *  *  **** ******* *   ** ****   ***   *  **   *   * ***    * ** * **** ** **  **  *       of %.2fx^2 + %.2fx + 1.00 = 0 are real and same\n",a,b,c);
      * **   *** *** *****  * *  ***     **** ******   *  * * * *  *** * **  ** *** **  *  **** *   = x2 = %.2f",x1);
 *** ** * ** * **** *    * *  **    * ***  ** *     *** * ***
   * *   ** ***  *        *   *
* *** **      **  ** *** * *     **  *** * * *** ***** 
**** ** ** *    *  * ** *  * * ** **   *  **        * * ****** *   ***    *   ***  ** *****   * **   ** *   of %.2fx^2 + %.2fx + 1.00 = 0 are complex and different\n",a,b,c);
* *   * *    *  **     **  **  * * *****    ** *****  ***  * ***  *****  *** ** *  *** ***   = * ***    * ***     *** *   **
 *******  ** * * * *    *** ** *  ** ** * * **   ** **** ** *  **** *      ***  * **   * *  =  ***  ***** **  **  * ** **
 * *   ***  * **    ** * *   ***  **    *   * * * *
 ** *  ** **   ** * ***    * * *  0;
}

Comments

prog.c: In function 'main':
prog.c:13:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are real and different\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:19:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are real and same\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:24:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are complex and different\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Answer 6

Hidden content!
  * *  * ***** * **
**  * *** *  *   *
int main()
{
* *** **  * *** ** ** * ***       a,b,c,D = 0,x1 = 0,x2 = 0;
   ** *** ***  ****   ** ****     ** *   *  *** *  *    * *** *   

* * * * *     *  **      *     * * * **** * of %.2fx^2 + %.2fx +%.2f = 0 * ***  *   *
*** ** *  ****  **  ** *** = (b*b-4*a*c);
  *  ***    ** *   *    * **  (D < 0)
**  ***        ***** **     
* ** *** * ** *   **  **** ** * ** *** * **  complex and  ******** **** 
 *** *  *   ****   *****    **** ** ** = * ***       ****    *** * ** *  
    *****    *  ******  ** *    * * **  =  ** **  * * *  * *  ***
  *  * **** * * * * *    ** * 
   *  ** **** * *** * **** (D > 0)
 ** * ** * * ***  **** *
 * * *  ** * *      * * * *** ***  * ** *     real and *  * ***** *  *  * 
 * *** **** *  *****      * ***  **   *    *    = ** ***   + sqrt(D))/(2*a));
 ***     *  * * *** ****** *  **  *  **    = %.2f",(-b - sqrt(D))/(2*a));
*        * *   *  **  ** ** 
*   *    *  ***    **** (D == 0)
 ****   *** *    ****** *  
*  * ***     *  **  ***    ** * **  *    *  real and same\n");
** *** *   ****  ***   ***     *     ** * = x2 = %.2f",(-b + sqrt(D))/(2*a));
** *    *** *  ***   *  *
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

---

your output lack of 1 space at line 8 when print out "Roots of ..."

Answer 7

Hidden content!
       ****        
*    * ********** *
int main()
{
 *  *     * *    *** *  *  ***   a,b,c,D = 0,x1 = 0,x2 = 0;
*** *  **   **    *  * * *    *******               ****   *   * *** **  *     

 * *** * *  **    **  * *    ***    ***     * of %.2fx^2 + %.2fx +%.2f = 0  *  ** *******  
 * **     **  *  *    = (b*b-4*a*c);
 *** *  *****   *  **  *    **  (D < 0)
* *  * * * *      * * 
**    ** ** *  ****  *   *****    complex and   *   ** ***  
    ** **      ** **  **  ***    **** **   * =   ****    *** *  **** *** **  * **
 * ** *  * * * ** *** * *  *  * * **       = ** ** * **  *  * ** *** **    ** **
** **   ** *** *  *** ** *     
 *  **  *** * * **   * * *  * (D > 0)
*** *  * ***   * *    ***      
  ** *** **  * *  * *      *  *  * real and * *  * *  *   *
*  **        * ** * *** ** * * **   =   ***       * *  + sqrt(D))/(2*a));
**** *   * * *** ** * * ***  ***** ** = %.2f",(-b - sqrt(D))/(2*a));
* ******  *   **** ** **   
* **  *****    * *  *  * **  (D == 0)
    **  ***** * *** *    *  
*  ***     ***  ***   ** **   *** *     *** real and same\n");
***  **** **   ***  *** ***   *  *  **  = x2 = %.2f",(-b + sqrt(D))/(2*a));
   * **  ** **  ** *  *  
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 8

Hidden content!
 **  *** ** * *   **
 * **   *  *   * *  ** *
int main()
{
 * * * *  *   **    *  *      * a,b,c,D = 0,x1 = 0,x2 = 0;
******  *  * ***  **  * *  *** ** ** * **    *  **   ****  * * *  **   *  * 

 * **  * **  *** **  ***** * **    ** *  of %.2fx^2 + %.2fx +%.2f = 0 ***    *     
*   **  **    ****   ****   * = (b*b-4*a*c);
     **  *     **  *  **  *    *  (D < 0)
 ** **     ***** * *       * *
 * * * *  * *  *   *  **** **** ** *  complex and *  *    **  *   **
 ***** ****    *   ***  * *  *   ** *** = *    * ** *  ** *  ***** *   
 **   ***     ****    *****   * *** * **  =   ******* *  ***  ** * *   * ****
*****   ***   *********   ***
 * *  ** * ** **  * * * *** * *  *    (D > 0)
**  ** ***** * * **    *
 * *    ** * **  *  **    * ** ** *    *   real and   * ***       * 
   *****    ** * *  * * *** *  **  ** =    ****     + sqrt(D))/(2*a));
** *  *** **** *  *****  *  * *  *  ****  = %.2f",(-b - sqrt(D))/(2*a));
* ***  *    *** ** *********  
 *  *  * ** *** ** * ******  (D == 0)
**  *   *   ****   *   * 
** *  ** **** ** ***  **   ****** *  * * real and same\r\n");
** * ** *** ** *  ** * **** **   ****** ** = x2 = %.2f",(-b + sqrt(D))/(2*a));
   **   ** ** * * ****  * *   
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 9

Hidden content!
* **  *** *** *****
** * *  *  * * *  * **
int main()
{
  *  **** *   * *  *  * *****  a,b,c,D = 0,x1 = 0,x2 = 0;
*** ******     * * ** ** * ** * *   * **** *****  ** *  * * ** ******  * 

* **   * ** **** * ****** **  *** * *   * of %.2fx^2 + %.2fx +%.2f = 0    **   ***
  *  *     ***     * **  = (b*b-4*a*c);
  * *   *  **    ** * *****   (D < 0)
* *    *      * **** * ***
* ****  * ********   * * ***** complex and *      *  ** ***
**          ** *   *  ***** * ****** **  =    *     *******     * * *  **    *  * 
**    * ****      **  ** *       * *   = ** *  *   **** *   * *** ***** * 
*  **  **** * **  ** *** **   *
  *  *   * ** * * *** * ** (D > 0)
 *       **** * * * ** *    
****  **  ****   ****** * **   * **  real and  *      ** ***
*  ***** **  *****   **    ** *  ***  =  *   **   * ***  * + sqrt(D))/(2*a));
* *  ** * *  *  * * **    * ** * *** = %.2f",(-b - sqrt(D))/(2*a));
  * * * ****  *** **   * ***
 *** **  *  *  **** *        *  (D == 0)
*** * ***   **** ***** 
*   *  *   ** ***    *  *  ** * **** real and same\r\n");
*** *  * ***  * ** **     * ** ****  = x2 = %.2f",(-b + sqrt(D))/(2*a));
** * ** **** **  ** * *
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 10

Hidden content!
 ** * *   **    *****
 ** ** ** * ****  * *  
int main()
{
**** **** **  ** ***  *   * ** * a,b,c,D = 0,x1 = 0,x2 = 0;
* ***         * * **   ***** **** *    *  * **   * ***** ** * *  **** * * ***    ** **

    ** ****    *  ** *****  *  **   ** of %.2fx^2 + %.2fx +%.2f = 0 are",a,b,c);
********    * **  ****    ** = (b*b-4*a*c);
* *  *  **  ** **  *  ****  * = (-b + sqrt(D))/(2*a);
*  ** * ** ** *****  ** *       = (-b - sqrt(D))/(2*a);
  **  * ***  ** *  **   ** ** (D < 0)
   * ***  **   * *    **  *
* ** **     ** * *  ***   *** *  *** *  complex and ** * **   **   *
 ***   *  ***   * * *   **   *  *** * = ** *  *  *       **** ** *    ** *  
    * ** ******* **    ** *   * *     * *   * * =     * **  ** ***** * * **      *
 ***** ** **    ***  *    ***
** **  * *    *  *  ***    * (D > 0)
* ** **   * ** ** **  ** 
***    **  *  *   **  * ***** **  * real and ** *   *   * 
   *  **  * *    * ** *** * * *** *     *    = ***** ***  *** *  
*** ** *  **** * **** **** **  **     * = %.2f",x2);
****   * *    *   *    
*   *   *  ** ***  * * * (D == 0)
 **   * ** ******     *   ***
    * *** *  ** **   **   *  **** *  *  **  real and same\r\n");
   *  **  * **** * ** * * * **** *  **** = x2 = %.2f",x1);
 **  * *   ** * * ** **      
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output