DynamicArrayInC.c

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

/*
 * This stores the total number of books in each shelf.
 */
int* total_number_of_books;

/*
 * This stores the total number of pages in each book of each shelf.
 * The rows represent the shelves and the columns represent the books.
 */
int** total_number_of_pages;

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;
    }

    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);
            int booksInShelf = *(total_number_of_books + x);
            *(total_number_of_pages + x) = (int*)realloc(*(total_number_of_pages+x),sizeof(int)*(booksInShelf+1));
            *(*(total_number_of_pages+x)+booksInShelf) = y;
            *(total_number_of_books + x) += 1;

        } else if (type_of_query == 2) {
          
            int x, y;
            scanf("%d %d", &x, &y);
            printf("%d\n", *(*(total_number_of_pages + x) + y));
          
        } else {
          
            int x;
            scanf("%d", &x);
            printf("%d\n", *(total_number_of_books + x));
        }
    }

    if (total_number_of_books) {
        free(total_number_of_books);
    }
    
    for (int i = 0; i < total_number_of_shelves; i++) {
        if (*(total_number_of_pages + i)) {
            free(*(total_number_of_pages + i));
        }
    }
    
    if (total_number_of_pages) {
        free(total_number_of_pages);
    }
    
    return 0;
}