└── dynamic array


/dynamic array:
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 1 | #include <stdio.h>
 2 | #include <stdlib.h>
 3 | 
 4 | /*
 5 |  * This stores the total number of books in each shelf.
 6 |  */
 7 | int* total_number_of_books;
 8 | 
 9 | /*
10 |  * This stores the total number of pages in each book of each shelf.
11 |  * The rows represent the shelves and the columns represent the books.
12 |  */
13 | int** total_number_of_pages;
14 | 
15 | int main()
16 | {
17 |     int total_number_of_shelves;
18 |     scanf("%d", &total_number_of_shelves);
19 |     
20 |     int total_number_of_queries;
21 |     scanf("%d", &total_number_of_queries);
22 |     
23 |     // Allocate memory for the total number of books per shelf
24 |     total_number_of_books = calloc(total_number_of_shelves, sizeof(int));
25 |     
26 |     // Allocate memory for the total number of pages per book per shelf
27 |     total_number_of_pages = calloc(total_number_of_shelves, sizeof(int*));
28 |     for (int i = 0; i < total_number_of_shelves; i++) {
29 |         total_number_of_pages[i] = NULL;
30 |     }
31 |     
32 |     while (total_number_of_queries--) {
33 |         int type_of_query;
34 |         scanf("%d", &type_of_query);
35 |         
36 |         if (type_of_query == 1) {
37 |             /*
38 |              * Process the query of first type here.
39 |              */
40 |             int x, y;
41 |             scanf("%d %d", &x, &y);
42 |             
43 |             // Increase the count of books on shelf x
44 |             total_number_of_books[x] += 1;
45 |             int size = total_number_of_books[x];
46 |             
47 |             // Reallocate memory to accommodate the new book
48 |             total_number_of_pages[x] = realloc(total_number_of_pages[x], size * sizeof(int));
49 |             
50 |             // Store the number of pages in the new book
51 |             total_number_of_pages[x][size - 1] = y;
52 | 
53 |         } else if (type_of_query == 2) {
54 |             int x, y;
55 |             scanf("%d %d", &x, &y);
56 |             printf("%d\n", *(*(total_number_of_pages + x) + y));
57 |         } else {
58 |             int x;
59 |             scanf("%d", &x);
60 |             printf("%d\n", *(total_number_of_books + x));
61 |         }
62 |     }
63 | 
64 |     if (total_number_of_books) {
65 |         free(total_number_of_books);
66 |     }
67 |     
68 |     for (int i = 0; i < total_number_of_shelves; i++) {
69 |         if (*(total_number_of_pages + i)) {
70 |             free(*(total_number_of_pages + i));
71 |         }
72 |     }
73 |     
74 |     if (total_number_of_pages) {
75 |         free(total_number_of_pages);
76 |     }
77 |     
78 |     return 0;
79 | }
80 | 


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