• C

# Can you improve it

hi,
I make a programme but I keep the feeling that it is not good. How you will make it:

You have a massive P[10][3] contains ten triangles(its sides):
side a=P[1][1], side b=P[1][2], side c=P[1][3]. Find whitch have max surface, and whitch have min surface.
You need to try if inpud numbers can be sides of triangle.

#include <stdio.h>
#include <math.h>

int main(void) {

float trian[10][3];
float a,b,c,p;
float S_max=0,S_min=1000,S_t;
int min, max;
for(int i=0;i<10;i++)
{

a=trian[i][1];
b=trian[i][2];
c=trian[i][3];

if((a+b)>c && (b+c)>a && (c+a)>b) // can be sides of triangle
{
p=(a+b+c)/2;
S_t=sqrt(p*(p-a)*(p-b)*(p-c));

if(min>S_t) {

S_min=S_t;
min=i;
}

else if(max<S_t) {
S_max=S_t;
max=i;
}
}
}
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Commented:
Hi

One error noticed instantly is

a=trian[i][1];
b=trian[i][2];
c=trian[i][3];

should be

a=trian[i][0];
b=trian[i][1];
c=trian[i][2];

Dhyanesh
Commented:
Hi

Few more errors. First of all initializing S_min to 1000 is an error. You could have the min surface area  triangle greater than 1000. You should increase this value to the maximum possible value. Another alternative is to assume the area of first triangle i.e. trian[0] as min and then continue comparing with others as you have done.

Also following lines have errors:

if(min>S_t) {                                         //should be    S_min>S_t

S_min=S_t;
min=i;
}

else if(max<S_t) {                        //should be  S_max<S_t
S_max=S_t;
max=i;
}

Dhyanesh
Commented:
Since you just want to find which triangle has min/max surface, you need not calculate the sqrt of the product. However, we need be careful here if there is overflow problem.
Commented:
Hi

You need not have an else after the if

if(min>S_t) {                                         //should be    S_min>S_t

S_min=S_t;
min=i;
}

if(max<S_t) {                        //should be  S_max<S_t
S_max=S_t;
max=i;
}

If an 'else' statement is put then first element will be set as minimum only. However first element is max as well as min

Dhyanesh
Commented:
#include <stdio.h>
#include <math.h>

int main(void) {

float trian[10][3];
float a,b,c,p,i;
float S_max=0,S_min=FLOAT_MAX,S_t;       //most compilers define constants for maximum value that a data type can hold ...
// check the header files stdlib or types.h
int min=-1, max=-1;

for(int i=0;i<10;i++)  //you had not declared i
{

a=trian[i][0];
b=trian[i][1];
c=trian[i][2];

if((a+b)>c && (b+c)>a && (c+a)>b) // can be sides of triangle
{
p=(a+b+c);                                    //you can get the result without the division
S_t=(p*(p-a)*(p-b)*(p-c));              // and ofcourse without the sqrt

if(S_min>S_t) {

S_min=S_t;
min=i;
}

if( max < S_t) {
S_max=S_t;
max=i;
}
}
}

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