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!
 ** ***  ***   **** *   * 
 ** **   *** **** 

int main() {
***     ** *   *     *** *   *    ** * ** *
 ** *** *****     **    **  * *** %f * **  *  *  &a, &b, ****   ** 
*  *  ** **   **  * *   * ******* * *   *
 * *     *   * ** ** **  **** *    * * {
    * ***  **** ** *   * ** ** * ***  **  *  *  ** ** ***   * **  *  **    of %.2fx^2 + %.2fx + %.2f = 0 are complex and * *   *  = *   ** ** =  ** ***** ***  a, b, c, (-b)/(2*a), * *****  (-b)/(2*a), *  ** *   *
 * *  **  ** * *   **  * * **    
*    *     *  ***  **  **** **    if(d==0) {
* *    *** **  * *** ******     *   **  * **  ****  **   *** **   **   * 
 **    * *   *     * ** *  *** ****   ** * *  **   *    *   **  *  *** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = ***  ***   a, b, c, x1);
***   **       **  *       *
    ***** * *   ***   ** * * * *** *** * {
  *** * *  *  *    * * ** * *** *   **  *     **       ** *  *** *   *** *  *
*  *  *  *   **** **** ** * ***   *  *   * *** * ***   * * ***    *  
***  ****   **  **** *  ** ** * *  * * *         ***  * **** *    * of %.2fx^2 + %.2fx + %.2f = 0 are real and * * *    = %.2f\nx2 =  ** *** * a, b, c, x1, x2);
*    ** * *    *     *  
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

Hidden content!
#include ***** **    *  *   
 * ***   * *  * ** **
#include    * ** *** 

int main()
{
**** **  * ** * ** * * **   *** * * 
   *  ********* ******* * *   ***  *    **  %f ******   ** * * *   ** ** **
**   ****** * *     *  * **** * ***
** ****       *  ** * *  *     * **    * * 
** *  **      ** **  ** *  * *  *  ** ****
***   * *  * *   * **   ****  *** 
  * * * * * ** *    * *** *  **   * * **  * of %.2fx^2 + %.2fx + %.2f = 0 are real and ***** ** * = %.2f\nx2 =   **** ** ***  * 
      * ** *** ***** *  *       if(D==0)
* ****  * ** * * **** * *  * ***    **** *  ** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = * ***** ****   **
*  *  *  **    * *  ** * * 
***   ****   *****  *  ****  **    ** * *   **** of %.2fx^2 + %.2fx + %.2f = 0 are complex and  **** * =  ***   = *** **  *   *** * * *   **         ** ** **  *    * *
   *** *   *    ** **** *  0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

Hidden content!
#include * ***** *    ***
  * **     *      **
 **    ** ****     ** *

int main()
{
 ** * *   *       * **** *      ** * *
**        ***     **** ** **   ** ***** %f *  **   *** * ****  ** * * ** 
**     **  *** ****** ** ** *  *  ***   
   * ** * **   *  * * ** * ** *  *  *********
*  *    **  ***   * *   **   ** * *
** *    * ** *   **   *     *      *   
**   * *** **** ****   *  **  ** *  ** ** * of %.2fx^2 + %.2fx + %.2f = 0 are real and  **  *    * = %.2f\nx2 =   *  **    * *
** ** ** **  * *  **** *  * *  * **** 
* ** *  * **      * **  * ** *    ** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = *   *  * * ** * **
  *      * **** *** ***  *  
*   **  **    ** ** *  *  *     * *** of %.2fx^2 + %.2fx + %.2f = 0 are complex and  *  **   * = %.2f + **** * = %.2f -  * **    ***  *  *  ****  ***  **   **  ** **
* *   *** ****  *    *  **  *** 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output

Answer 4

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include<math.h>
int main()
{
** ** ***    *   ** *   * ****  a,b,c,x1,x2,D;
 **    *** ** *****  **  * *   **  %f ** **   * *     ***  * 
* * ** *** *     *  ***    **  * ** 
*     **  *  *  *  *  *  *    = (-b + sqrt(D))/(2*a);
** *  * *  *  *    **** *  *   = (-b - sqrt(D))/(2*a);
 *  **  *  * *  **** *       *  ***   * * *
   ******    *** *  * **     ***** **  *  *  ** * * *   *** 
* *****   * **      ***    ** * * **  *   ***  ** ***** ** *  *  *  *   *   ***** ** * **      ** **  of %.2fx^2 + %.2fx + %.2f = 0 are real and different\n",a,b,c);
 ******* ***   ****** *  *  *  * **     * *** *  *   * ************ *** ***    *   ****  * = %.2f\n",x1);
**      *** *** * * *  *****  **         *  **   * *   * ** ******* *  ** ***** *    ***   = %.2f",x2);
 ***  * * ***  ** ****  **** *  *    *       **  *  **
***    * *   * ***  **   * *  ***  *  if(D==0)
 ** ** *** **  ** *  ** *  **  **    *  *   ** ****** **  
*    ******** * *    ***  **** *** *** ***  **        ***** **  * *  ** ** ** ***   * * *  of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
* *********   **   ** ******  *    * **** *   ** ** **   *    *  *  * ***  *  *** *** = x2 = %.2f",x1);
*  *   ** * ** *   *   *** * ** ** * *   **  ** * ***  *** 
* **   *  ** *** * * *     *** ** **
*** *** **     * * *  * **  ** **  ** ** *** ***** *  
**** * *  ** * ** *****  * *  **** *  ** ** * **** *** **  *    **  *  * * *** * * ** ***** *    *** *** **** of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\n",a,b,c);
 **  *    **** **   * *  * * * ** *   ** ** ***  *    *  ******  *  * *   * * *    ** *** *   *  =  * *  ** * * *** ***  *** * **
* * **  **     * *******    ****   * **** *   **    *  **   ** **    ***   *     *** * = * * *   ** **   ** * *   ** ** * *
  ** *   *  * ***** *  **  *** *      **** *  *  ** * * ** * 
 * * *    **  *      *    ** * *   0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 5

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include<math.h>
int main()
{
* *** *** ** ** ** * ** *  * a,b,c,x1,x2,D;
* **  * * ** *   ** *** ****  *   *   ** %f    * **   * *       **    *** 
**** **** ** *     ***** *   * **  
*** ***** *****  ** ** ** **** = (-b + sqrt(D))/(2*a);
* * ** ****    *  *      * = (-b - sqrt(D))/(2*a);
*****      **  * *  * ** *       ** * 
* **  * *  ** *  **  *  *    **  ** ** * * * * *****   *  *
* * *   *** ** * * **  **   **        ** **  *  *  *    *** *   *  ** *  * *** ******  * ** of %.2fx^2 + %.2fx + 1.00 = 0 are real and different\n",a,b,c);
*  * ** * **  *** ***   *   **** *** * *** ****    * *   ** ** ***  * **     *  *   *      * = %.2f\n",x1);
* *  * * * **     *** * *  * ** ** * * ****   *  ******* ***  *  * *  *** *  *     * *    *  = %.2f",x2);
*   *  **** * * *****  * *  ******  ** ***** **    ****
**  * ***  ***   ***      * *   if(D==0)
*   *   **  *****   *  ** *  *** ** * *   **    **        *  
   ***    *****     *** ***     ** ** * ** * * * * *  *    *  *  **   * *  * *     *  * *** * of %.2fx^2 + %.2fx + 1.00 = 0 are real and same\n",a,b,c);
 ***  *   ****    ****   ** ***  ** * * * **  *** * * *    *  * * *** *****     *  **  ***** * *   = x2 = %.2f",x1);
*  ****      *  ** * *     **  *   **  ** **** *    **  
*** *** * * *    *  *   ** 
* ***    * ** ** *******    *    *** *  * * **  ******
  *   **      * *     * ***      * *  *     *** ****  * **  * *     *   **  * *  * **  **  *  **  * * of %.2fx^2 + %.2fx + 1.00 = 0 are complex and different\n",a,b,c);
    ** ** * ***    * **** *  ***** * *** *    * **  * *      **  *** * **   *** **  * *  * ****     = *   *     * *  *   ** ** ***
 *****   * *    *   * ** * ** *         * **   ** *       ** * * *** ***    ****   *** * * **  * *  =    ** * ** *** *   * * *  *** *  
 *****   * *   *  *  ***** ***** * * *    **   * * * 
 *** *  *  * * * *** **  * **** * 0;
}

Comments

prog.c: In function 'main':
prog.c:13:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are real and different\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:19:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are real and same\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:24:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are complex and different\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Answer 6

Hidden content!
*** *  ***  *    *    
   * ** * *** ***      
int main()
{
   **     *  **  * ***** * a,b,c,D = 0,x1 = 0,x2 = 0;
***** * ** * *  * **    *  **    *  * **     *** ** ****  **  **  **** ** **

   *  ********      ** ** *  **    *****    ** of %.2fx^2 + %.2fx +%.2f = 0 **  ** ** ** 
*********  *        *   ** * = (b*b-4*a*c);
* * * * **        * *   * (D < 0)
* *** ** * **   * *    **   
**** **    *  * **   *  *** * *** **** *  complex and   *   *       
 ***   * * ** *    ** ** * *** *   ** ** =  * * ****  **** ** *********  * * *
**   * **  *  *** **  *** * * **    ** =  ***  * *** * *   ** * * * 
 **** **   *** * **  **  * *
   *  *   *   * * * *   *    *  * (D > 0)
* **  ** * *  ***   * *  *
**** ** *     *    *** *  *  ***  * ** ** real and ****   * * ****
  *      *  *   * ***  *****   *    **  *** = ** *   **** + sqrt(D))/(2*a));
 ***  *   **  ***    ******  **** *    * * **  = %.2f",(-b - sqrt(D))/(2*a));
***   *   * ******** * *** ** 
 *    *  * *  *  *****  *  *  (D == 0)
      *  ***** *   * * 
*   ***** **** *   *    *      **    * * real and same\n");
***** ** **   * * ** * * ****  *      * * * = x2 = %.2f",(-b + sqrt(D))/(2*a));
  **  *** * * * ***  * ** *
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

---

your output lack of 1 space at line 8 when print out "Roots of ..."

Answer 7

Hidden content!
*  *   *  **  ***** 
*   ******  * * ** * 
int main()
{
 **  *   *  ***  ** *  **  a,b,c,D = 0,x1 = 0,x2 = 0;
** * * ** **     ****    *  ****  * **********    *  ** *  **  ** *   

 ** *   * *  **  **   *  **** * * ***** *  * of %.2fx^2 + %.2fx +%.2f = 0     * ***** ***  
  *   * * *       *   **  * *  = (b*b-4*a*c);
*  ** ********  ** *    *  (D < 0)
 *  *** **  ** *** ** * * ** *
 * ** ** * **  *  *******  * *   ** * * complex and *  * *   *     *
 *  *** *   *** * **     ** * *  * *  =  * ** *****   *  **  * **** * *  *  
** *******  ** *  ** *******  ****  * = ** *    ** * *      *         
  ***** ****  **     **   ***
 *      ** * **  *** *  * *   (D > 0)
  **  *****  * ** * ****  **
 *** *** *  * **  **   ****** ****       *** real and    ****  * * 
** **  * ** * *** *  *** *  ** ****   ** = *  * **  ***** + sqrt(D))/(2*a));
  ** *  * ****   *  *  **   *** *** ***** ** = %.2f",(-b - sqrt(D))/(2*a));
*          *  **     * * **  *
* ***  * **  *** **** ***  (D == 0)
***   * *  *   *  * **    
  *    *  **  *  **  **  ** **  * *** *  real and same\n");
  ******* **  *     *   ** *  *   *   ** * = x2 = %.2f",(-b + sqrt(D))/(2*a));
**** ***   **  ** **  *** 
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 8

Hidden content!
 *  ** * * ** * 
* *  ** *   *  * * *     *
int main()
{
*** *  *     *****    **    *    a,b,c,D = 0,x1 = 0,x2 = 0;
 **  ****  ** * ***  *  ***  *       ***  *   * *      ** **  ***** 

* *  *    * **  *  **  ** * **     *    * **  of %.2fx^2 + %.2fx +%.2f = 0 *** ****    * **
* *  * ** *   * **  ****** *  ** = (b*b-4*a*c);
  * ***   *** *** **** * ***  (D < 0)
* * *   **** **    * ** ****
*     ***  **   ***   **  **** * **  * * *  complex and *  *  **   **  *  
****  *** *  ******   **      **** * *     =  **** *   **** *** * *    * * * 
*     **    ***** * *  *  * *  *    **    * * * = ****    **  * *  ** ***** * 
* ** *  ***** * * ** **** 
****** *     **  *** *   * *   (D > 0)
   *** * *     * **  * *    
* *  * **  *    * *   *  **    **   real and * * *   ****  
* ** ** * *****  **  * * ***  * *   ***  = ****  * *** ** ** + sqrt(D))/(2*a));
     **   *  *     *  *** ** **** *** *** ** = %.2f",(-b - sqrt(D))/(2*a));
***  ** * **  *     * * ** * *
  ** *   *** *     ** (D == 0)
  *   * *** **  **   *  *  * ** 
*** * ******* * *** * *** ** * ** ** real and same\r\n");
* **** ********* *******   **  *    = x2 = %.2f",(-b + sqrt(D))/(2*a));
**   *** *        **** *   *  
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 9

Hidden content!
* * ****  *******   
  *  *    * * **   * 
int main()
{
 ***       ******   ****    * a,b,c,D = 0,x1 = 0,x2 = 0;
  *****   *** *****   * ***   *   * * * ****   ***  *  *  * **    ****

  ***   ******* *     *  *  * *     *  of %.2fx^2 + %.2fx +%.2f = 0    ** *    ***  
*  * ** *  * * * *   ** **    = (b*b-4*a*c);
** *** ** * ****           (D < 0)
***    *******  * *   * **   *
*** **** *   **** * ** *  ** * **  ***  complex and  *** ***  ** *   ** *
*      *   * * *  *** ** *** * **** = **** ***  *** **  * ** ** * *  *    *
   * ** *****  * ** **  **** **  **  **** ** =  ***  *  * ** ***  *    *
  * ***  ***   ****  * *** *
* *   * **   ** * ****  ** (D > 0)
* *   ****  *** **** **  * *   *
** *   ** *     *   *  *** ** *** ** **** real and  * * * * * *******
**** *      * **   ** * **   ******  =  **** *  *  *** + sqrt(D))/(2*a));
** ****       * *****    ** ******* = %.2f",(-b - sqrt(D))/(2*a));
** ***  *  * *  ***   *** **
***  * * * *  **   * * *   (D == 0)
** ** ***  *           
** *** **   * * * **** ***  *  *   * **     * real and same\r\n");
   * **** *     *  ** *   *  *   * **  *  = x2 = %.2f",(-b + sqrt(D))/(2*a));
* ***** ****      *   *   * *
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 10

Hidden content!
  *  * *** *******
 * *****  **    ** * *
int main()
{
    *   * ****      *  *   ***  a,b,c,D = 0,x1 = 0,x2 = 0;
*** *   **** **   **    * ** **  *****  ** * ** * **  * * ** *  **  ***  

  *  * ** *      *   ***  * **  *** ** *   ** of %.2fx^2 + %.2fx +%.2f = 0 are",a,b,c);
**  ***** *** *  ****   *** = (b*b-4*a*c);
*  * ****   ** * * * *       = (-b + sqrt(D))/(2*a);
*          *** * *** *    ****  = (-b - sqrt(D))/(2*a);
* * ****   * **       * *  *** * (D < 0)
    **   **   ****  ** * * ** 
*****    *  * *  *  **** * **  *  ** complex and *** *  **  *
     ****  **   *   * *  *  *  *****  **  * = ** * *  **    *   *    *    *  **  
*  **** *****  **    **** *   ** ***** * *  **  * = *****  * **  * ******     
*  * * **  * *     ***  *   
 *****  ** * * ** ***  * (D > 0)
*    **  **   *   *  *** 
  * *  *  *   * *   * * **      **** **  real and *** *  *** * **** **
 ** **   *  *  * *** *  *** ** * * *   = **  * **    * * 
 **** ** **   * *** ** **** * ***   **  **  * = %.2f",x2);
   * **   ***** ** *** * *   
* * **   ** * **      * ***** * (D == 0)
*** ** **   * * * * ****
 * **   **  ** *********  *  *   ***  real and same\r\n");
* ** ********   * * **** *      *   *   = x2 = %.2f",x1);
* *** **  *    ** * * *
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output