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