initial commit

.gitignore

@@ -0,0 +1,3 @@
+# ignore input files and objects
+*.o
+*.input

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.12)
+project(aoc2019 C)
+
+set(CMAKE_C_STANDARD 99)
+
+add_executable(day1 day1/day1.c)
+add_executable(day2 day2/day2.c)

day1/day1.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+    unsigned sum = 0;
+    while (1) {
+        int a = 0;
+        scanf("%d\n", &a);
+        if(!a) { break; }
+        while (a > 6) {
+            a = (a / 3) - 2;
+            sum += a;
+        }
+    }
+    printf("Sum: %u\n", sum);
+    return EXIT_SUCCESS;
+}

day2/day2.c

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+//
+// Created by red on 02/12/19.
+//
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+void print_elems(long* arr, size_t n);
+long run(const long* input, size_t n, long noun, long verb);
+
+int main() {
+  char input_str[350];
+  memset(input_str, 0, 350*sizeof(char));
+  long input[140];
+  char* ptr = input_str;
+  size_t i = 0;
+  scanf("%s", input_str);
+  while (*ptr != 0 && input_str - ptr < 350) {
+    input[i] = strtol(ptr, &ptr, 10);
+    i++;
+    ptr++;
+  }
+  size_t size = i;
+  long out = run(input, size, 12, 2);
+  printf("Value of mem[0] with noun=12, verb=2: %ld\n", out);
+  for (i = 0; i < 100; i++) {
+    for (long j = 0; j < 100; j++) {
+      long out = run(input, size, i, j);
+      if (out == 19690720) {
+        printf("Noun+verb found! n: %ld, v: %ld\n", i, j);
+        return EXIT_SUCCESS;
+      }
+    }
+  }
+}
+
+long run(const long* input, size_t n, long noun, long verb) {
+  long mem[n];
+  memcpy((void*) mem, (const void*) input, n*sizeof(long));
+  size_t ptr = 0;
+  mem[1] = noun;
+  mem[2] = verb;
+  while (ptr < n) {
+    long opcode = mem[ptr];
+    if (opcode == 1) {
+      long a = mem[ptr+1];
+      long b = mem[ptr+2];
+      long c = mem[ptr+3];
+      mem[c] = mem[a] + mem[b];
+      ptr += 4;
+    } else if (opcode == 2) {
+      long a = mem[ptr+1];
+      long b = mem[ptr+2];
+      long c = mem[ptr+3];
+      mem[c] = mem[a] * mem[b];
+      ptr += 4;
+    } else if (opcode == 99) {
+      return mem[0];
+    } else break;
+  }
+  return -1;
+}
+
+void print_elems(long* arr, size_t n) {
+  puts("Printing elements of array");
+  for (size_t i = 0; i < n; i++) {
+    printf("%ld ", arr[i]);
+  }
+  puts("");
+}