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