In this tutorial, I will give a **solution** for **HackerRank Dynamic Array** in **c problem** with practical program code example and step-by-step explanation. in this problem we need to read an integer value that denotes the number of shelves in the library, the second integer denotes the number of requests and then we need to read a number of queries. we need to write a logic to place the book at the respective shelf.

## Problem solution in c programming

```
#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;
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;
} 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;
}
```

it shows segmentation fault.

please check again