124 lines
3.3 KiB
C
124 lines
3.3 KiB
C
#include <stdio.h>
|
|
// #define INPUT_LENGTH 5000
|
|
#define INPUT_LENGTH 7
|
|
#define DEC_KEY 811589153
|
|
|
|
struct list_node {
|
|
struct list_node* prev;
|
|
struct list_node* next;
|
|
long value;
|
|
};
|
|
|
|
void mix_right(struct list_node* node, long amount) {
|
|
struct list_node* new_prev = node->next;
|
|
// Pop from position
|
|
node->prev->next = node->next;
|
|
node->next->prev = node->prev;
|
|
// Advance from original next to the new prev
|
|
for (int i = 1; i < amount; i++) {
|
|
new_prev = new_prev->next;
|
|
}
|
|
// Set node to have correct new links
|
|
node->prev = new_prev;
|
|
node->next = new_prev->next;
|
|
// Insert after new prev
|
|
new_prev->next = node; // same as node->prev->next = node;
|
|
node->next->prev = node;
|
|
}
|
|
|
|
void mix_left(struct list_node* node, long amount) {
|
|
struct list_node* new_next = node->prev;
|
|
// Pop from position
|
|
node->prev->next = node->next;
|
|
node->next->prev = node->prev;
|
|
// Advance from original prev to the new next
|
|
for (int i = 1; i < amount; i++) {
|
|
new_next = new_next->prev;
|
|
}
|
|
// Set node to have correct new links
|
|
node->next = new_next;
|
|
node->prev = new_next->prev;
|
|
// Insert after new prev
|
|
new_next->prev = node; // same as node->next->prev = node;
|
|
node->prev->next = node;
|
|
}
|
|
|
|
void mix(struct list_node* node) {
|
|
int forward_amount = node->value;
|
|
int reverse_amount;
|
|
const int mod = INPUT_LENGTH-1;
|
|
if (forward_amount == 0) return; // Do nothing for 0
|
|
if (forward_amount > 0) {
|
|
forward_amount = forward_amount % mod;
|
|
reverse_amount = mod - forward_amount;
|
|
} else {
|
|
reverse_amount = -forward_amount % mod;
|
|
forward_amount = mod - reverse_amount;
|
|
}
|
|
if (forward_amount < reverse_amount) {
|
|
mix_right(node, forward_amount);
|
|
} else {
|
|
mix_left(node, reverse_amount);
|
|
}
|
|
}
|
|
|
|
int main(int argc, char *argv[]) {
|
|
struct list_node code[INPUT_LENGTH];
|
|
struct list_node* zero; // Keep track of this node for later
|
|
long coord_x, coord_y, coord_z;
|
|
// Initialize circular doubly-linked list links
|
|
code[0].prev = &code[INPUT_LENGTH-1];
|
|
code[0].next = &code[1];
|
|
for (int i = 1; i < INPUT_LENGTH-1; i++) {
|
|
code[i].prev = &code[i-1];
|
|
code[i].next = &code[i+1];
|
|
}
|
|
code[INPUT_LENGTH-1].prev = &code[INPUT_LENGTH-2];
|
|
code[INPUT_LENGTH-1].next = &code[0];
|
|
|
|
// Init sample
|
|
code[0].value = 1;
|
|
code[1].value = 2;
|
|
code[2].value = -3;
|
|
code[3].value = 3;
|
|
code[4].value = -2;
|
|
code[5].value = 0;
|
|
code[6].value = 4;
|
|
zero = &code[5];
|
|
|
|
// // Load input
|
|
// FILE *fp = fopen("input/20", "r");
|
|
// for (int i = 0; i < INPUT_LENGTH; i++) {
|
|
// fscanf(fp, "%ld", &code[i].value);
|
|
// if (code[i].value == 0) {
|
|
// zero = &code[i];
|
|
// }
|
|
// }
|
|
// fclose(fp);
|
|
|
|
// Part 2 execution
|
|
for (int i = 0; i < INPUT_LENGTH; i++) {
|
|
code[i].value = code[i].value * DEC_KEY;
|
|
}
|
|
for (int pass = 0; pass < 10; pass++) {
|
|
for (int i = 0; i < INPUT_LENGTH; i++) {
|
|
mix(&code[i]);
|
|
}
|
|
printf("Resulting chain from mix %d: ", pass);
|
|
for (int i = 0; i < 7; i++) {
|
|
printf("%ld ", zero->value);
|
|
zero = zero->next;
|
|
}
|
|
printf("\n");
|
|
}
|
|
// Get resulting coords
|
|
for (int i = 0; i < 1000; i++) {zero = zero->next;}
|
|
coord_x = zero->value;
|
|
for (int i = 0; i < 1000; i++) {zero = zero->next;}
|
|
coord_y = zero->value;
|
|
for (int i = 0; i < 1000; i++) {zero = zero->next;}
|
|
coord_z = zero->value;
|
|
printf("Part 2: coords (%ld, %ld, %ld) give sum %ld\n", coord_x, coord_y, coord_z, coord_x+coord_y+coord_z);
|
|
return 0;
|
|
}
|