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