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