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

struct Node {
	int value; 
	struct Node* next; 
};

// Note: this may look like a constant based on naming convention, but without
// `const`, it's actually declared as a global variable
int kNumElements = 20;

struct Node* make_list() {
	// Make a list with one element
	struct Node* front = malloc(sizeof(struct Node));
	front->value = 0;
	front->next = NULL;

	struct Node* end = front;
	// Tack on 19 elements to the end of the list
	for (int i = 1; i < kNumElements; i++) {
		// Allocate a node and add it to the end of the list
		end->next = malloc(sizeof(struct Node));
		// Now, this new node is the end of the list
		end = end->next;
		// Initialize the new node
		end->value = i;
		end->next = NULL;
	}

	return front;
}

void swap_tenth_node(struct Node* list) {
	// Go to the 10th node
	struct Node* curr = list;
	for (int i = 0; i < 10; i++) {
		curr = curr->next;
	}

	// Replace the next node
	struct Node* nextNext = curr->next->next;
	curr->next = malloc(sizeof(struct Node));
	curr->next->next = nextNext;
	curr->next->value = 100;
}

/**
 * Program is going to create a linked list with 20 nodes. Then, it will
 * replace the 10th node with a different one, and finally print/free the list.
 */
int main() {
	struct Node* list = make_list();

	// Swap a node
	swap_tenth_node(list);

	/* Print and free everything */
	struct Node* curr = list;
	while (curr->next != NULL) {
		printf("%d\n", curr->value);
		struct Node* next = curr->next;  
		free(curr);
		curr = next;
	}
}