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