Add c implementation for day1

day1/c/day1.c

@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int calculate_fuel1(int mass)
+{
+    return mass / 3 - 2;
+}
+
+int calculate_fuel2(int mass)
+{
+    int fuel = mass / 3 - 2;
+    if (fuel < 0)
+        return 0;
+    else
+        return fuel + calculate_fuel2(fuel);
+}
+
+int main(void)
+{
+    FILE *fp;
+    char *line = NULL;
+    size_t len = 0;
+    ssize_t read;
+
+    fp = fopen("../input", "r");
+    if (fp == NULL)
+        exit(EXIT_FAILURE);
+
+    int fuel1 = 0;
+    int fuel2 = 0;
+    int mass;
+
+    while ((read = getline(&line, &len, fp)) != -1) {
+        mass = atoi(line);
+        fuel1 += calculate_fuel1(mass);
+        fuel2 += calculate_fuel2(mass);
+    }
+
+    printf("Solution for Part One: %d\n", fuel1);
+    printf("Solution for Part Two: %d\n", fuel2);
+
+    fclose(fp);
+    if (line)
+        free(line);
+
+    return 0;
+}