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

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Everything is fixed. Enjoy your time with The Judge :)

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ANNNNNNNNNNNNNNNNNNNNNNNNNNGRYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

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Your code has newline at the end sometime. You learned this lesson many times!

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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.

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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 <stdio.h>
** * * * ** *    *  ** * 
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Comments

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

Answer 2

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#include <stdio.h>
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{
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Comments

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

Answer 3

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#include <stdio.h>
#include <stdlib.h>

int main()

{
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Comments

prog.c: In function 'main':
prog.c:12:14: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
     x1=(-b + sqrt(D))/(2*a);
              ^~~~
prog.c:12:14: warning: incompatible implicit declaration of built-in function 'sqrt'
prog.c:12:14: note: include '<math.h>' or provide a declaration of 'sqrt'

Answer 4

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}

Comments

prog.c: In function 'main':
prog.c:6:5: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
     scanf("%f%f%f",&a,&b,&c);
     ^~~~~
prog.c:6:5: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:6:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:12:9: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
         ^~~~~~
prog.c:12:9: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:12:9: 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 complex and different\n",a,b,c);
         ^~~~~~
prog.c:17:9: note: include '<stdio.h>' or provide a declaration of 'printf'
prog.c:23:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\n",a,b,c);
         ^~~~~~
prog.c:23:9: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 5

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int main()
{
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}

Comments

prog.c: In function 'main':
prog.c:8:12: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
     x1=(-b+sqrt(D))/(2*a);
            ^~~~
prog.c:8:12: warning: incompatible implicit declaration of built-in function 'sqrt'
prog.c:8:12: note: include '<math.h>' or provide a declaration of 'sqrt'

Answer 6

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main()
{
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Comments

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

Answer 7

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
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Comments

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

Answer 8

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#include *** ***   *  *
#include *      * **   *

int main()

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}

Comments

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

Answer 9

Hidden content!
#include  ***  * ****  ** *
#include ** ** *   *  ****
int main(void)
{
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}

Comments

prog.c: In function 'main':
prog.c:10:16: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
         x1=(-b+sqrt(D))/(2*a);
                ^~~~
prog.c:10:16: warning: incompatible implicit declaration of built-in function 'sqrt'
prog.c:10:16: note: include '<math.h>' or provide a declaration of 'sqrt'

---

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

---

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

---

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

---

prog.c: In function 'main':
prog.c:21:5: error: expected ';' before '{' token
     {
     ^

---

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

---

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

---

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

Answer 10

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

int main()
{
* **** **** *  **   * **  * *** a, b, c, ** *   * x1,x2, realPart, * ** ** * 


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**  *   *   *  *** **    *  
** *****  *** **    *** *  *  * *    *  ** * **    **** ** = x2 = -b/(2*a);
   *    * *   *******  *   * *****  ** *** * * ** ** * * ** ** *  of %.2fx^2 + %.2fx + %.2f = 0 are real and     ***   ** a,b,c);
   **********     ***      ** ****  ****  *  **     * *** * ** ** **  = x2 =     * **  x1);
*  * ****  ***  **  ******* *  *

   *  *  ***     **** *   ***   ** *** if (determinant > 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: Correct output
Case 2: Correct output
Case 3: Correct output