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