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  1. Prepare
  2. C
  3. Arrays and Strings
  4. Dynamic Array in C
  5. Discussions

Dynamic Array in C

  • tpgreene
     + 63 comments

    The default code doesn't malloc the total_number_of_books and total_number_of_pages for you. It just declares them in the global space. So you have to do that first before doing the query==1 section.

    I used the more esoteric notation for pointers, but array style also works (and is easier to understand). So total_number_of_pages[x][total_number_of_books[x-1]]=y; is also legit. The reason the x-1 is used instead of x is because, while they pass in the books according to their index value (0 instead of 1), they perform the queries by the actual physical amount of books (1 instead of 0).

    int main()
{
    int total_number_of_shelves;
    scanf("%d", &total_number_of_shelves);
    
    int total_number_of_queries;
    scanf("%d", &total_number_of_queries);
    
    total_number_of_books=(int*)malloc(sizeof(int)*total_number_of_shelves);
    
    total_number_of_pages=(int**)malloc(sizeof(int*)*total_number_of_shelves);
    
    for(int i=0; i<total_number_of_shelves; i++){
        total_number_of_books[i]=0;
        total_number_of_pages[i]=(int*)malloc(sizeof(int));
    }
    
    while (total_number_of_queries--) {
        int type_of_query;
        scanf("%d", &type_of_query);
        
        if (type_of_query == 1) {
            int x, y;
            scanf("%d %d", &x, &y);
            *(total_number_of_books+x)+=1;
            *(total_number_of_pages+x)=realloc(*(total_number_of_pages+x), *(total_number_of_books+x)*sizeof(int));
            *(*(total_number_of_pages+x)+*(total_number_of_books+x)-1)=y;