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