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