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