Thread: optimising program

  1. #1
    Registered User
    Join Date
    Mar 2008
    Posts
    7

    optimising program

    I have developed following program which takes two sets as input and
    returns union and intersection set.

    Code:
    #include <stdio.h>
    #include <conio.h>
    #include <math.h>
    #include <stdlib.h>
    
    typedef struct set
    {
       int order;
       int *ele;
    };
    
    
    /* Function Prototypes */
    
    struct set _union(struct set, struct set);
    struct set _isect(struct set, struct set);
    void display(struct set);
    void getdata(struct set*);
    
    
    int main()
    {
        struct set s1, s2, s3, s4;
        int i,j;
        system("CLS");
        
        printf("\nSET 1:\n");
        getdata(&s1);
        printf("\nSET 2:\n");
        getdata(&s2);
        
        s3 = _union(s1, s2);
        system("PAUSE");
        printf("\n\nThe union is:\n");
        display(s3);
    
        
        s4 = _isect(s1, s2);
        printf("\nThe intersection is:\n");
        display(s4);
        
        system("PAUSE");
        return 0;
    }
    
    
    /* display() :  displays the set. */
    
    void display(struct set t)
    {
         int i;
         printf("\n{ ");
         for(i=0; i<t.order; i++)
         {
             printf("%d",t.ele[i]);
             if(i+1 != t.order)
                 printf(", ");
         }
         printf(" }");
    }
    
    
    /* getdata() : gets set data. */
    
    void getdata(struct set* t)
    {
         int i;
         
         printf("\nHow many elements:   ");
         scanf("%d",&t->order);
         t->ele = (int*) malloc(sizeof(int)*t->order);
         printf("\nEnter elements:  \n");
         for(i=0; i<t->order; i++)
         {
               scanf("%d",&t->ele[i]);
         }
    }
    
    /* _union() : returns union of two sets */
        
    struct set _union(struct set A, struct set B)
    {
         int i,j;
         struct set C;
         
         /*Maximum no of elements in union set of two set is sum of order of that 
          two sets */
         C.ele = (int*) malloc(sizeof(int)*(A.order+B.order));
    
         
         
         C = A;           /* Copying first set into union set */
         
         
         
         /* Elements in set B which are not in set A are copied to union set */
         
         for(i=0; i<B.order; i++)
         {
              for(j=0; j<A.order; j++)
              {
                    if(B.ele[i] == A.ele[j])
                        break;
                    else
                        continue;
              }
              
              if(j == A.order)
              {
                   C.ele[C.order] = B.ele[i];
                   C.order++;
              }
         }
         
         return(C);
    } 
              
         
    
    /* _isect() : returns intersection of two sets */     
        
    struct set _isect(struct set A, struct set B)
    {
         int i,j,k,temp;
         struct set C;
         
         /*Maximum order of intersection set of two set is least order among that 
           two sets */
           if(A.order > B.order)
              temp = B.order;
           else
              temp = A.order;
         
         C.ele = (int*) malloc(sizeof(int)* temp);
         C.order = 0;
         
         
         /* Elements which are common in both sets are copied into _isect set */
         
         for(i=0; i<A.order; i++)
         {
             for(j=0; j<B.order; j++)
             {
                    if(A.ele[i] == B.ele[j])
                    {
                     /* Check for avoiding multiple addition of number into set */
                         for(k=0; k<C.order; k++)
                         {
                             if(C.ele[k] == A.ele[i])
                                  break;
                             else
                                  continue;
                         }
                         if(k == C.order)
                         {
                              C.ele[C.order] = A.ele[i];
                              C.order++;
                         }
                    }
             }
         }
         
         return(C);
    }
    this programs works well but i wonder if i can optimise functions _union() and _isect().
    plz give me suggestion.

  2. #2
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Location
    Singapore
    Posts
    28,413
    this programs works well but i wonder if i can optimise functions _union() and _isect().
    Sort then compare in a single pass.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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