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);
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~