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Posted on 2003-11-26
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Last Modified: 2010-04-15
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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Comment
Question by:sisqu
6 Comments
 
LVL 4

Expert Comment

by:dhyanesh
ID: 9824006
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
0
 
LVL 4

Expert Comment

by:dhyanesh
ID: 9824041
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
0
 
LVL 2

Expert Comment

by:htang_us
ID: 9824829
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.
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LVL 4

Assisted Solution

by:dhyanesh
dhyanesh earned 250 total points
ID: 9825144
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
0
 
LVL 45

Accepted Solution

by:
sunnycoder earned 250 total points
ID: 9825304
#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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Author Comment

by:sisqu
ID: 9829239
Thank you all (dhyanesh, htang_us and sunnycoder)
 for professional look, you give me good ideas. I cant deside who give the points and divide it to both.
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