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