1 files changed, 68 insertions, 0 deletions
diff --git a/4/part1.c b/4/part1.c
new file mode 100644
index 0000000..7b53e3c
--- /dev/null
+++ b/4/part1.c
@@ -0,0 +1,68 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+bool is_valid_passport(const char *pass)
+{
+    return strstr(pass, "byr:")
+        && strstr(pass, "iyr:")
+        && strstr(pass, "eyr:")
+        && strstr(pass, "hgt:")
+        && strstr(pass, "hcl:")
+        && strstr(pass, "ecl:")
+        && strstr(pass, "pid:");
+}
+
+int count_valid_passports(const char *filename)
+{
+    FILE *file = fopen(filename, "r");
+
+    // Include space for newline and string terminator
+    char buffer[128] = { 0 };
+
+    bool has_byr = false;
+    bool has_iyr = false;
+    bool has_eyr = false;
+    bool has_hgt = false;
+    bool has_hcl = false;
+    bool has_ecl = false;
+    bool has_pid = false;
+    int correct = 0;
+    while (fgets(buffer, 128, file)) {
+        if (buffer[0] == '\n') {
+            if (has_byr && has_iyr && has_eyr && has_hgt && has_hcl && has_ecl && has_pid) {
+                correct++;
+            }
+
+            has_byr = false;
+            has_iyr = false;
+            has_eyr = false;
+            has_hgt = false;
+            has_hcl = false;
+            has_ecl = false;
+            has_pid = false;
+        }
+
+        has_byr = has_byr || strstr(buffer, "byr:");
+        has_iyr = has_iyr || strstr(buffer, "iyr:");
+        has_eyr = has_eyr || strstr(buffer, "eyr:");
+        has_hgt = has_hgt || strstr(buffer, "hgt:");
+        has_hcl = has_hcl || strstr(buffer, "hcl:");
+        has_ecl = has_ecl || strstr(buffer, "ecl:");
+        has_pid = has_pid || strstr(buffer, "pid:");
+    }
+
+    if (has_byr && has_iyr && has_eyr && has_hgt && has_hcl && has_ecl && has_pid) {
+        correct++;
+    }
+
+    fclose(file);
+
+    return correct;
+}
+
+int main()
+{
+    printf("%i", count_valid_passports("input"));
+}