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!
#include    *  *** *   **
#include  *  * ** ***   *

int main()
{
 ****   **   *     *   **     a, b, c, determinant, x1,x2, realPart, *      *


 * **** * **   ***** *  ****** *** *** %lf  ***   *  * * *  *    &b, &c);


  *** ** *     * *    *    ** * * = b*b-4*a*c;

    * ***  **  *** ** *  ** *   condition for real and different roots


* *****   *  * ***    * *   *  ** **** * for real and equal roots
  ** *  ** *   * * *  ****    *  **   *  **  (determinant == 0)
* *******   ** ** ** * * **   
** ** ******* ****** * * *     *** * **  ** * * **  * ** ** = x2 = -b/(2*a);
* * * ** **  *  * *  *   *** * ** **  * **** *  ** ** ** **   *    of %.2fx^2 + %.2fx + %.2f = 0 are real and **   *  a,b,c);
**        *  **  * * * *    *    * ******    ***   *  *  *  ****   * = x2 =  ** * ***  x1);
**** *** **  *  * ***   *

   ** ** ** **   **  *       ** *   *  if *  **  > 0)
 **   **** **** *    *    *
* * ** ***   ****  **** * * sqrt() function returns square root
 * ** *** *   *  *    ** * **   **  **  **    ***   * ** = *   ** ***    * *   
***  *    *  *   *** * ** * ** **** * ***  *  ***  ****  *   = **   **    ** * *  

 **  *  *     *   *  ** * ****  *  * *  *****   *   *  ***  *    *** ** * * *  of %.2fx^2 + %.2fx + %.2f = 0 are real and * *  ** ** **  * **
**    * * * *   *  * ***   **  * *   ****    * ****   ***    ** * = **** * *  * x1);
 ** *  ** *  *    **  ** * **    **** * ***   * **   *****   ****  * * *** * *  = **  ***   * x2);
  ****** ***** **        if roots are not real
 **** *  *   * ***** *  *   *   **  
*   * * ** **  *  **  *** ** ** 
  *******  *****  * *** ******* **  *****  **   **** * * *    *  * = -b/(2*a);
 ***    * * *       *    **   *** ** * *** *   **** **** *    = **  *  *  * 
* * ** ** *  *  ***   * ** * * **       **  * *   *  *  *     *     of %.2fx^2 + %.2fx + %.2f = 0 are complex and  * * ** * * * * * a,b,c);
  **    *    *   *      * * * **  * **** * *   *    ** **  * *    *** * = **    * * *  **** realPart, * * *** *** 
 ***  ** **   **  *  *** * **   ** * *   *  ** *  * *  *****  * =   **   *   realPart,    ** *  **  
  ** ** * *   *   *  * *  *

    **  **   * * *  **  ** *  *  0;
}

Comments

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

Answer 2

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

int main()
{
 ***** *      *** *  *   **** * a, b, c, determinant, x1,x2, realPart, **** * ** 


  *  * **  *****  ** * ** *   *         %lf  *    * *  ** *  &b, &c);


** *  *  ** * ** *     *   ** ** ** ** = b*b-4*a*c;

   *** ****   ***  *  ******  condition for real and different roots
** ***  * ***    * ** *     ** (determinant > 0)
*** **  ***   *** ****  
* *  ***   ****  * * * *** sqrt() function returns square root
 * **    * * * ***  **     * **  *   * *     * *  *  *   *  = * ***    ** *      **
* ** ***         **  *   **  *   ***  ** * ***  * **  ** =      **    *      

 *  *** *  * *** *  ** *   ****  *  *  * * *  *  *  *  *   *   *****  *** of %.2fx^2 + %.2fx + %.2f = 0 are real and ******  *   * * **   
 *       *  ***** **  ***** ****  ***    **   *  * *  *   **  * ***   = *   * *  x1);
 * ** **  *   **** **  ***   *****  * *  *    * * *** ** * ** **    * =   **   **  x2);
 *** *  ** *   ** * *  * **

*  *****  ** *  ****** * * *  * ***** for real and equal roots
* ** ***     **    * **   * * if (determinant == 0)
 *  *  *** *    ** ** *   **
 ** * ***   ** * * * *     *  ** **  * * * ** * *** ** = x2 = -b/(2*a);
***** * ****   **** ** * *  * * *******  * * * * ** * ** * * **  *  of %.2fx^2 + %.2fx + %.2f = 0 are real and    ***  * *   a,b,c);
** *** * * **   **** **  *  *  * * * *  *   **    **  *  *** **   = x2 = * * **     * x1);
 ******** ** ***** **

  ** **   * ** *******  ** if roots are not real
* ** *****   ** ***  *  *  * ** 
  * * *  *** **   ***  * ** 
          *   *** * * ** *   ***  ** **** * * ** *  = -b/(2*a);
    * ** **  ** *  * *     *  ****  **   *** * **       = **** *  *** **
 * * **** *      * *****    ** ** * *    ***    ***  **  * *  ** *   ****   of %.2fx^2 + %.2fx + %.2f = 0 are complex and   ***  * * **    a,b,c);
*    * *      **   *   ***  **  *** * * ** ****    **      **** * *** = **  *      *  realPart, ***  **** 
*  *      ** * * * **** * * * * ****** ****  ***** ** *  * *     *  * =  *** **   ** * realPart,   **  * *
  ********  ** *      ** 

******  *  * *     *** **  ** * 0;
}

Comments

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

Answer 3

Hidden content!
 *   **  *** * * 
          *  ** *   **
int main(void)
{
*** *     *  ** * *     *  * * a,b,c,d;
*  ** ** *** **  **    ***** *** ** * **   %f   ****   *   * **       ***  *
 ** **** ***      ** *  * **   * * ***
* ** * ***   **** ****  * **   ****      
  **   * ***  **  *   *  ****    **   **   *** * ** *  * *   ** **** of %.2fx^2 + %.2fx + %.2f = 0 are real and ***** *  = %.2f\nx2 = **** * ***  ** +  **  *   **** -         * *
*  *  *** *  * * ** **  ** ***
**   ** *     *   * *   ** **** * (d==0){
** **    *  ****  ****  *  ** * *   ****   ****  *     *  *   *    ** * * ** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 =      **** ** + ***  **    *
  *    * * * * ** *** ** *  
 * *  ** **   * * ***     *** (d<0) {
******** **  ****** ***** **  ***    **         ***  * * ***   of %.2fx^2 + %.2fx + %.2f = 0 are complex and *  * ** = *   * * = * * * *  * *       **  ** ** * ** ***   *  ** **    ***
 **  * ****** **   *  ** *   
}

Comments

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

Answer 4

Hidden content!
       * *    **** **
*    **** *  *  
int main(void)
{
** * **   ** * ****** ***** a,b,c,d;
  *  *  *   * ***  * * **  * *          %f **  **** **  ********* *   *  **    
**      ****   ********  **  *** *****
 *  *  **  *    ** ** **  ****  (d>0){
      *  *   **   **  * *** ***   *  *  * ** *   *    * ** * * * * *  *** * of %.2fx^2 + %.2fx + %.2f = 0 are real and  *       = %.2f\nx2 = **  ***    ****  +     * *  *     - ** **  *  
  *  *  ** ***** ** ****
 *   *******    ******* *   ** ** (d==0){
     ** *   ** * ***** *  *  *** ***     ******    *  * *    **      * *    of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = *    *** *  *** +        * 
 * * *  **  **  ****   *  
   **** *** **  *** * ** ** * {
    * *   *  **   *  ****  **      * *   *  ** * **   ** *     **   ** *** of %.2fx^2 + %.2fx + %.2f = 0 are complex and  *     **  * = * ***   =   *  ***    ***   *** ** *     ** *** **** *  * **  **   * **
* *** *  *  *  * *   **** **
}

Comments

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

Answer 5

Hidden content!
#include<math.h>
int main()
{
 *** *****  *  **  ** ** *** **  a,b,c,d,x1,x2,x3,x4;
***** ***    *   ****  * *  * *  * **** * %f * * *    *      *   **  * *   *
   *********   *  ***  * * ****** **
 * *    *  *  *  ***  * *  **  ** **    
  * *  *   **   * ** *  ** ** *   *** * ****
*   *** *   * ***   *  ***  *
 * *  * ******  *** *  * ****** *   *  
*  *  * ** * * ****  *** *  ** *  * * *  *   *
*    * **  **** ***    *  * * *
*** * * **  * ** *   * *  ***   **   ***  * **** **   * *****  *     of %.2fx^2 + %.2fx + %.2f = 0 are real and  * **  * **  *  * * ****     ** 
    *** *  *  * *   *  ** *
     *  ***** *    **  * *    *  ******* ****  **
* ***** ** * ** *    *     *
*  * * ***  *  *** ** * ** *   ** * *  * ****   **    *  *    *   of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
** ** *** *** * *     * ***
*** *   *     **    ** ***  *     * **  *** ** ** * *   * *
    ****  * * * * ** ****  ** 
 *  * *  **    * **     *   * *  *  **  * **     ****  **  ** ***** * of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2 = ** **  *** ****  *   ***   
********        **   ** 
     * * **** * *****  ** *    * **** 0;
}

Comments

prog.c: In function 'main':
prog.c:5:5: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
     scanf("%f %f %f",&a,&b,&c);
     ^~~~~
prog.c:5:5: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:5:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:13:9: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are real and different\nx1=%.2f\nx2=%.2f\n",a,b,c,x1,x2);
         ^~~~~~
prog.c:13:9: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:13:9: note: include '<stdio.h>' or provide a declaration of 'printf'
prog.c:17:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
         ^~~~~~
prog.c:17:9: note: include '<stdio.h>' or provide a declaration of 'printf'
prog.c:21:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2 = %.2f-%.2fi",a,b,c,x3,x4,x3,x4);
         ^~~~~~
prog.c:21:9: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 6

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
   * *** * * *   **  ** *        a,b,c,d,x1,x2,x3,x4;
* * **    * ***     ** * *** ***   ***  * %f *  *   * ***** *** **   *** **
*   ** * *      * ** *** ***    **  
 *   ***   * * * *   **** *  ********
      *** ** ******* *** *  * ** ***   ***** **  ** *
 **  ********* * *  *   * *  *   * ** *  
 *   **  ** * *   *  ** *         ***** *
** ****  *  ***  *  * *  **  *  *     ** *  *  *   *  *  *** 
 *****   *** *** ****  ** 
  **  ** *    * * * *        *     * *    *    *** ** ****  * *    **  of %.2fx^2 + %.2fx + %.2f = 0 are real and ***   *    ****     **    *** * * ***  
*  * * ** ** **  *    ** * *
   *  ***  * * * ***  **     **** ***  ********     *** *
***  **** *  ****   **  *  *    
     *  *    **  ** ***  **   ** * *  ***  ** *      * * ** ** *  of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
  * **  *** *  ** **  *   ** *
 *   *   * *******  *   * ** *** * * ** **  ***  * ** * ** *** *
**   ***** * *   * ******   * *
  ** *   ***** *     * *  * * *** **** * ** *****  *  *  * **    of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f + %.2fi\nx2 = %.2f - *  * *    *  * * *  * ****
  *     ******  **   **** **
 * * * * ****  * *  *   **  ** *  0;
}

Comments

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

Answer 7

Hidden content!
#include<stdio.h>
    *** **  *** * * * 
int main()
{
 *****   ***  * * *    *** ***  * * a,b,c,d,x1,x2,x3,x4;
 *     *  *  * *   ** *** *    ** ** * ** %f * ****   *** *** **  **  * * * 
*  **   ******** *  **** **    
* **** *     ***   ** ** ******   **   **   * 
*   * * ****   *  ** ** * **** * **  **
*  * ***** *    * * **   **** ** **   
**  * * *   **** * **** * **** * ******
 *  *  * *******  *  * ** **  ****  *   ** ******* **
*   * *    * **    *     
 ****  * ** *   * ******** ******  **** ****    * *  * **      * of %.2f x^2 + %.2f x + %.2f = 0 are real and * * * ** ***    *  *           * **** * *  *
 * *    **  * *** * ***** *   *
*  *        ***   *   ** * **   * * *  * *   * 
** *   ** * * *   ** *    
* **    ** ***  ** *  ** *******  **   ***     * * ** * ***  *** of %.2f x^2 + %.2f x + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
  ** ***   ***   * **  ***   *
 *** * * * **  * * *  ** ****** *******  *  ** *   ** 
***  *  * * * * ** ****     *  *   **
** *   **  *  ** **  **** *    **  * *  *  *** *  * ***    *  * *   * *   of %.2f x^2 + %.2f x + %.2f = 0 are complex and different\nx1 = %.2f + %.2fi\nx2 = %.2f - ****       *   *  *    
  *  *** *  * * ** ** * *** 
 *     * **  * * **      * 0;
}

Comments

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

Answer 8

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
****     *   * *****  *** *   a,b,c,d,x1,x2,x3,x4;
 **** ** * **    ** *  ****  *   *  **   ** %f * *     * ** **** *   ** **  *
 * ***** ******** *  * * ***  
*   * ***** ** * * * ***    *  ** ****
 * **     *  *  * *** * * **   ****    * ** *
      **   ** *  *   *     ** *    *
*  ****  **  * * * *  * *** *  *  * * 
*** ****    * * *     **    * **  *** * *  * *  * * *   *  **
 **  ***  ****** **** *  **
*    * *  *** *****   * * *      ** *  *   **    **** * * ***** ** ** **    of %.2f x^2 + %.2f x + %.2f = 0 are real and * ** ***      * ***** ******    **
 *  *** * *  *  * ** * *
***  * **  **    *** ** ***   *   **  * ** * ** * *
 **     * ** *** * ****** * 
*   *** ** ****      *****  * ***      ***    **   **** **  *   **         of %.2f x^2 + %.2f x + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
**  **   **  ** * *   * **
*  * *  ***  * * ******* ** **     ** *    * * *  **** ***
**   ** *  ***      *  **   *** 
* **         ** * ***** *  ***  *** ***   ** * * **  *** *   **** *   of %.2f x^2 + %.2f x + %.2f = 0 are complex and different\nx1 = %.2f + %.2fi\nx2 = %.2f -      ***  * **   **** *   *
 ********  ******* *       *
*  ***   *   ****   **  *** ***********   *****   **  
* * * *** ** **** * ** *  *  * * * 0;
}

Comments

prog.c: In function 'main':
prog.c:24:5: warning: implicit declaration of function 'system' [-Wimplicit-function-declaration]
     system("pause");
     ^~~~~~

Answer 9

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
   * ** *** ** ** ** *   * **    a,b,c,d,x1,x2,x3,x4;
  * * ***   **  * **   *   *     **   ** %f    ** *  ****** *      **    *  
 *  *** * ** * * **   **   *     *  *
  * * *****  *** *****  * ** * ***** ***   
  *  ** * ** ****   *   ******  **   ***  
*** * ** ** *     * ** ***** * 
*  ** ** ** * *** *     ** *   * ***  
   * **  ** * *   ** *** *   *** ***** *  **  **  *   *   
* * *  ******  **   * *  
** **  ** *  ** **   * *  *  ******  * ****** ** * ***** **  of %.2f x^2+%.2f x+%.2f=0 are real and different\n x1=%.2f\n ** * *  * **  ***      
  **** **   * *      ** * *
 * ** * ** **   ** *    * **  *  **   * ** **** *  *
* *  * * ***  ** * ***  ***
***   ** **  ***    *   **  *** *  **** *   * *  ** ** ** *  * * of %.2f x^2+%.2f x+%.2f=0 are real and same\n  ** ** ** *  ** *** * 
**  *    ** ***** *  **
* * * **  * ***   * * * * *  **   **   ** *   ** *
*  * *   *     **  * **
* * ****** **    **  *  * * **   ** ** ***  * ** **     * ** *  * of %.2f x^2+%.2f x+%.2f=0 are complex and different\n x1=%.2f+%.2f i\n x2=%.2f-%.2f  ** **  ***    ** *
*    *  ***  *  *** * ** *
*   *** **  * *  * **** **  ****  0;
}

Comments

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

Answer 10

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
* *****    ** * *** * *  ** a,b,c,d,x1,x2,x3,x4;
 **  ***    *  **  ** *** ** *** ***** **    %f    *  * ** **** * *     *  ****
** *** *  **** ******   *    
**** **   * *  *  * ***  ***   *** *  * 
*  * * *******        *** ****   *** * **** *
*  *    *  ** * *** * *     *    **
******    *   * * *  ** **  **     ***
 * *    *    *  **  **** * *** * *   *  *   ***     
 ******* **   *** * **     *
****  * *** *   * ****  *  **   **    *** * ****       **** **   * *  of %.2f x^2+%.2f x+%.2f=0 are real and different\n x1=%.2f\n ** ** * * ** *   * * 
***  ****** *** ** * ** 
*    ** **  ** *   * *   *** * ***** *  **  * * *  
* *    ** * ****   *  ****  *
  *  **  ** *    ** *   * ** *  **** *  ***  * ******     ****   * of %.2f x^2+%.2f x+%.2f=0 are real and same\n ** * **    *  * **    
 ****** ** ***  * ** * * *
**  **** * * ** *  * *  *    ** ***    *  * * * *** ** ********
 * * *  **    *   *  *   *   *
 *      *     ** *  ** * * * * ** ***  * * *****  ***  ** ****    ** of %.2f x^2+%.2f x+%.2f=0 are complex and different\n x1=%.2f+%.2f i\n x2=%.2f-%.2f * *      **   ** ** 
*** *   *   ***  *      ** **
**  **  * *  *  *  *  *  *  * ***  ** 0;
}

Comments

prog.c: In function 'main':
prog.c:18:16: warning: too many arguments for format [-Wformat-extra-args]
         printf("Roots of %.2f x^2+%.2f x+%.2f=0 are real and same\n x1=x2=%.2f",a,b,c,x1,x2);
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~