Add Day 8 solution

Author: JohnnyJayJay

Day-08/c/JohnnyJayJay/Day08.c

@@ -0,0 +1,93 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "../../../shared/JohnnyJayJay/aoc.h"
+
+typedef struct {
+ char* opcode;
+ int arg;
+} instruction;
+
+typedef struct {
+ int* possible_corruption;
+ int possible_corruption_len;
+ int acc;
+ int infinite_loop;
+} execution_result;
+
+execution_result* run_program(int length, instruction* insts) {
+ int* visits = calloc(sizeof(int), length);
+ int acc = 0;
+ int* possible_corruption = malloc(sizeof(int) * length);
+ int possible_corruption_len = 0; 
+ int infinite_loop = 0;
+ for (int i = 0; i < length; i++) {
+ if (visits[i]) {
+ infinite_loop = 1;
+ break;
+ }
+ visits[i] = 1;
+ instruction* inst = &insts[i];
+ char* opcode = inst->opcode;
+ int arg = inst->arg;
+ if (strcmp(opcode, "acc") == 0) {
+ acc += arg;
+ } else { 
+ possible_corruption[possible_corruption_len] = i;
+ possible_corruption_len++;
+ if (strcmp(opcode, "jmp") == 0) {
+ i += arg - 1;
+ }
+ }
+ 
+ }
+ free(visits);
+ execution_result* res = malloc(sizeof(execution_result));
+ res->possible_corruption = possible_corruption;
+ res->possible_corruption_len = possible_corruption_len;
+ res->acc = acc;
+ res->infinite_loop = infinite_loop;
+ return res;
+}
+
+void free_execution_result(execution_result* result) {
+ free(result->possible_corruption);
+ free(result);
+}
+
+void fix_program(int length, instruction* insts, int* possible_corruption, int possible_corruption_len) {
+ for (int i = 0; i < possible_corruption_len; i++) {
+ int pos = possible_corruption[i];
+ instruction old = insts[pos];
+ instruction new = {strcmp(old.opcode, "jmp") == 0 ? "nop" : "jmp", old.arg};
+ insts[pos] = new;
+ execution_result* result = run_program(length, insts);
+ int infinite_loop = result->infinite_loop;
+ free_execution_result(result);
+ if (infinite_loop) {
+ insts[pos] = old;
+ } else {
+ return;
+ }
+ } 
+}
+ 
+
+int main(int argc, char** argv) {
+ FILE* file = fopen(argv[1], "r");
+ int lines = count_lines(file);
+ instruction* insts = malloc(sizeof(instruction) * lines);
+ for (int i = 0; i < lines; i++) {
+ char* opcode = malloc(4);
+ int arg;
+ fscanf(file, "%3s %d", opcode, &arg);
+ instruction inst = {opcode, arg};
+ insts[i] = inst;
+ }
+ 
+ execution_result* result = run_program(lines, insts);
+ printf("The accumulator is %d\n", result->acc);
+ fix_program(lines, insts, result->possible_corruption, result->possible_corruption_len);
+ result = run_program(lines, insts);
+ printf("The fixed accumulator is %d\n", result->acc);
+}