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