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