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